This word conjures such legalistic images of long dresses, no makeup, and rules about what you can and cannot do: such as watch television, go to a dance, or play games. Anything that seemed fun was frowned upon. Those who were mired in “Holiness churches” have vowed to stay away from anything resembling holiness. As a result, some because of the wrong ideas of holiness have gone to the other extreme where anything goes.
However remember the admonition of the Apostle: Make every effort to live in peace with all men and to be holy; without holiness no one will see the Lord (Heb 12:14). Holiness is so important that without it, you will not see the Lord, either here in this life or the life to come. People wonder if they could enter heaven even if they are living a very sinful life. The Bible gives clear warnings about failing to enter heaven because of a life of sin:
The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions  and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God. (Gal 5:19-21) 
I did not write this. Paul did, so if you do not like what he wrote, talk to him about it. I am only the messenger boy. If this passage is not enough, how about this one:
Instead, you yourselves cheat and do wrong, and you do this to your brothers. Do you not know that the wicked will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral nor idolaters nor adulterers nor male prostitutes nor homosexual offenders nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God. (1 Cor 6:8-10)
This is a warning to believers, for he says, "You yourselves cheat and do wrong, and you do this to your brothers." It’s clear that Paul was warning the church.
I also understand that any sincere believer can fall and make mistakes. God will not be quick to judge us. He promises to stay married to the backslider. Turn, O backsliding children, saith the LORD; for I am married unto you (Jer 3:14, KJV). God will not divorce His backslidden children; however, His children may divorce Him. True children will repent and follow the way of holiness, and thus be saved. Make no mistake about it, do not be deceived: holiness is essential for salvation.

Holiness is like a Marriage

Holiness is two fold: it is separation from the world in order to be joined to the Lord. The picture is of a marriage. In a marriage, a wife and husband “forsake all others and cleave unto each other.” A couple is not really joined if all they do is abstain from seeing other people, but never intimate with each other.
Holiness has unfortunately been associated with separation from the world and sin, but not being joined to the Lord in intimacy. Intimacy makes holiness enjoyable. If you are always concentrating on what you cannot do, then you will be unhappy with holiness. It is like a married couple that does not cheat, but neither do they sleep with each other. Is that good? They never slept with anyone else, but if they don’t have intimacy with each other, then they have only half of a marriage.
Some Christians have only half of a relationship with God. Abstinence from sin is meant to open you to God. When you live a sinful life, then the sin takes away your attention and allegiance from God, and so your relationship with Him suffers.
People often ask me, “Why can’t I do this or do that?” and they usually refer to sinful things. It is because those things become like a mistress or gigolo that draws away your affection from God. Eventually you will find yourself more interested in the sin than in cultivating your relationship with God.
The truth of the matter is, most sincere believers get entice with sin because their relationship with God has suffered. You hear a straying spouse say, “It was not this other woman that broke up my marriage, because my marriage was already in trouble.” The same is true of sin; most people fall into sin because they are not cleaving unto God in intimacy. This is why you must cultivate a relationship with God through reading the Bible, praying, fellowshipping in church and producing good fruit especially winning souls. When you constantly do these things you will not be as susceptible to sin, plus you will draw closer to God.
Don’t use what I wrote as an excuse to allow sin to stay in your life. Make no mistake about it; sin will cause your love for God to grow cold. It may be true the marriage was in trouble before the other woman came into the marriage, but the other woman has definitely made the marriage worse. Sin is like that. Your relationship with God may already be in trouble, but sin will make it worse.
Holiness enables you to see
The most important thing you need to do to get close to someone is to “see” them. Long distance relationships are difficult to maintain. The same is true of God. You must “see” the Lord if you want to get close to Him. The Hebrew writer plays on the word “see.” Without holiness no one will see the Lord. He could have said no one will be “saved”, but instead he chose the word “see”, because this word implies a relationship, not just trying to please God so you can be saved. Notice how often he uses the word “see” in this chapter.
v. 15 "See to it..."
v. 16 "See that no one is sexually immoral..."
v. 25 "See to it that you do not..."
Holiness will open your eyes to see how great God is and how awful worldliness is. Sin will blind you to several important truths, yet holiness will enable you to see several things.

1. See the precious grace of God.

Hebrews 12:15 says, “See to it that no one misses the grace of God…”
There was a man who was given a very precious and expensive bowl, but he did not know what it was to be used for, so he used it as an ashtray. This is what happens when Christians go into sin with the belief that God will be quick to forgive them, so they cleverly use the grace of God to practice immorality. They rationalize their behavior, “Well, no one can really be perfect anyway, so since God will forgive anything I might as well do anything.”
Jude verse 4 warns against this type of thinking: “For certain men whose condemnation was written about long ago have secretly slipped in among you. They are godless men, who change the grace of our God into a license for immorality and deny Jesus Christ our only Sovereign and Lord.” You can use the grace of God to “say no to ungodliness” or make it a license to give you permission to say “yes to immorality”. (see Titus 2:12)
When you have a license for something, you are apt to use it to do what you are licensed to do. For example, before you received a driver’s license, you rarely or never drove, but when you got your license, you drive all the time. Jude warns against certain teachers who are encouraging the saints to sin. They teach in such a manner that believers feel it is alright to sin.
In my senior year of high school there was a substitute teacher who began to talk about Jesus. I was excited to hear her because I was a “turned-on” believer. A student asked her, “Is it alright to smoke pot and still be a Christian?”
The teachers shocked everyone, “Of course, in fact I smoke pot. You see, it doesn’t matter what you do, it only matters what you believe. So long as you believe in Jesus, you will be saved, even if you do things that seem wrong.”
It is this type of teaching that the Apostle warned against. True faith will lead to a lifestyle change. This teaching really denies that Jesus Christ is our Sovereign and Lord. People ask me, “Do you believe in Lordship salvation?” What they mean by the question is do you need to make Jesus Lord to be saved, or can He just be your Savior and not Lord?
Paul answers this question in Romans: “That if you confess with your mouth, ‘Jesus is Lord,’…you will be saved” (10:9). It is not enough to confess that He is your Savior; He must be your Lord in order to be your Savior. Jesus will not be your Savior if He is not your Lord. Jude tells us that people who change the grace of God into a license for sin do not have Jesus as their Lord, and he says their condemnation is long over due.

2. See the defilement of bitterness.

Hebrews 12:15 says, “See to it that no one misses the grace of God and that no bitter root grows up to cause trouble and defile many.”
When a person pursues holiness, he sees more clearly his own weakness, therefore is patient when others harm him. Show me a person who is bitter toward another, and I will show you someone who is not grateful to God for their own forgiveness.
Bitterness has caused many believers to fall away from God. They will stop going to church because of a certain member in the church has hurt them. When you understand the high price Jesus paid so you can be forgiven, you will be so overwhelmed by His mercy toward you that you will be quick to forgive anyone of anything they did toward you.
Jesus gave a parable to illustrate this. Jesus explains that there was a king who began to settle accounts; a man who owed him millions of dollars was brought to him. Since he was not able to pay, the master ordered that he and his wife and his children and all that he had be sold to repay the debt.
The servant fell on his knees before him. “Be patient with me,” he begged, “and I will pay back everything.” The servant's master took pity on him, canceled the debt and let him go.
But when that servant went out, he found one of his fellow servants who owed him a few bucks. He grabbed him and began to choke him. “Pay back what you owe me!” he demanded.
His fellow servant fell to his knees and begged him, “Be patient with me, and I will pay you back.”
But he refused. Instead, he went off and had the man thrown into prison until he could pay the debt. When the other servants saw what had happened, they were greatly distressed and went and told their master everything that had happened.
Then the master called the servant in. “You wicked servant,” he said, “I canceled all that debt of yours because you begged me to. Shouldn't you have had mercy on your fellow servant just as I had on you?” In anger his master turned him over to the jailers to be tortured, until he should pay back all he owed.
Jesus concluded the parable by saying, “This is how my heavenly Father will treat each of you unless you forgive your brother from your heart.” (Matt 18:24-35)
This man did not appreciate the King’s forgiveness and so in self righteousness he began to mistreat a man who had wronged him in the past. Many Christians act the same way. Instead of showing appreciation for God’s mercy on their souls, they react poorly to those who have sinned. When you pursue holiness you are gentle and forgiving toward others.

3. See the high cost of sexual immorality.

Hebrews 12:16 says, “See that no one is sexually immoral…”
There is an absolute epidemic in the body of Christ. It has become a cancer and is spreading quickly throughout the church and even its leadership; it is sexual immorality. If we do not cut it out soon it will destroy the body of Christ.
There is no doubt about it; we live in an unprecedented age where sexual immorality is all around us. You cannot even drive in your car without seeing images of sexuality. Pick up a newspaper and it is there. Watch TV and it screams at us. Go to a ball game and it dances before us. Open email, and it pops out in front of us. It is impossible to live in this age without seeing those images, and so it should not shock us to see sexual immorality as being the most prevalent sin in our day. It is.
We need to understand the high cost of sexual immorality. Look at TV ministries that are no longer in existence or has lost its visibility, and you will know there is a high cost of falling for this sin. In case the world winks at this sin, God makes sure that there will be a price for sexual sin: for God will judge the adulterer and all the sexually immoral (Heb 13:4).
Gays may be marching for their rights, but they have the lowest lifespan of any group in our country. No one can mock God when it comes to sexual immorality. High profile ministries have sometimes used their status to solicit sisters in Lord. They thought they would get away with it, but bam, judgment came.
Don’t misunderstand me, God is forgiving, He will forgive any repentant believer, but, even though God forgives, there is often a high price to pray for indiscretion. Sometimes God may use the Law to bring judgment. I have known people who took advantage of children and now they sit behind bars. They use to sit behind pews, but not anymore. We must take a warning and flee sexual immorality.

4. See the benefit of faith

Hebrews 12:16 says, “See that no one is sexually immoral, or is godless like Esau, who for a single meal sold his inheritance rights as the oldest son.”
To be godless does not mean you are an atheist but it means you live like God does not exist. Hebrews tells us that God rewards those who trust him. Often, Christians get discourage when they don’t see God’s blessings for living for Him. Sometimes they sell their birthright to enjoy the pleasures of sin, but the pleasures last only for a season. Soon they discover how far they have fallen.
Sometimes people have fallen so far that they lose any real desire to change. This is what happened to Esau. He lost his birthright, and so he pleaded with tears to get it back, but he could not bring himself around to truly change. for he found no place of repentance, though he sought it carefully with tears (v. 17, KJV).
Kenneth Hagin told the story of a woman evangelist who was mightily used of God. She had a tremendous healing ministry. One day she left her husband and children to pursue an illicit sexual rendezvous with a married man. People tried to talk to her out of it, but she refused to listen. Hagin began to pray for her and while praying he had a vision. In it, he saw a man come to her door and she opened it, dressed in an open robe. The man at the door tried to persuade her to leave the man but she said, “Listen: get out of here. I don’t want anything to do with you and your God.” She had totally abandoned the faith she once preached.
Salvation is like a coal. Holiness is like a diamond. You may be saved, but through the Lord’s discipline and godly pressure, the coal can turn into a diamond. Do not be satisfied simply with being saved, desire holiness as well.

You see, without holiness you cannot “see” the Lord. You are blind to your own failures and sins and are cold in your relationship with God.  I encourage you to pursue true holiness with God and you will be greatly rewarded by the Lord.