To the angel of the church in Pergamum write: These are the words of him who has the sharp, double-edged sword. I know where you live--where Satan has his throne. Yet you remain true to my name. You did not renounce your faith in me, not even in the days of Antipas, my faithful witness, who was put to death in your city--where Satan lives.
Nevertheless, I have a few things against you: There are some among you who hold to the teaching of Balaam, who taught Balak to entice the Israelites to sin so that they ate food sacrificed to idols and committed sexual immorality. Likewise, you also have those who hold to the teaching of the Nicolaitans. Repent therefore! Otherwise I will soon come to you and will fight against them with the sword of my mouth.
Whoever has ears, let them hear what the Spirit says to the churches. To the one who is victorious, I will give some of the hidden manna. I will also give that person a white stone with a new name written on it, known only to the one who receives it.
~ Revelation 2:12-17
So at first, this letter it a bit confusing. It has many references to people and practices that you may not have even heard of before. Yet ignorance of these practices is unimportant; it is entirely possible to understand the gist of the letter without fully understanding what is going on. But this is 2012, we have the internet, so we have the opportunity to easily understand these archaic references.
But let's start at the beginning. The church of Pergamum is said to exist in the city of Satan's throne. In otherwords, this city is about as far removed from God as possible. It was the official center of emperor worship, exalting the emperor as a god, and the citizens practiced all sorts of sinful lifestyles. And yet, in the midst of all this, a church grew and prospered, enough to be chosen as a recipient of this letter. And this is what Jesus saw with such great promise from this city, that these people defended their faith always, and it never wavered. Even under threat of abuse and death, such as what happened to Antipas, the first martyr, these people did not renounce their love for God. These people know of the inconceivable treasures that wait in heaven, and they know that if they want to share in these gifts, they must give up all selfish desires to follow God completely.
And yet, this is where the church falls short. While they know that the treasures in Heaven are greater than the pain they suffer on this earth, they do not deny themselves the sinful pleasures of Satan. They have memebers of the church who eat food sacrificed to idols: the act of eating this food in itself in not a sin. In 1 Corinthians 8, Pau talks about this exactly. He says that idols are nothing, and therefore it means nothing for food to be sacrificed to it, and therefore nothing when that food is eaten. And yet, he advises against it, for the eating of food is directly related to idol worship, and for those who do not know that this practice is not sinful, may cause them to question your morals, even so much as to believe you worship the idol of the food you are eating. There are also people who practice sexual immorality: In this time, public orgies were often one method by which they would please their gods. And finally, there are the Nicolaitans: they were a religious sect that used their faith and belief in God's saving grace as a justification to sin, so that they may live as the pagans to and yet still recieve eternal life.
And the problem with this lifestyle is that as Christians we should not continue to live a life of sin. Galatians 2:20, we have been crucified with Christ, and with it have become dead to sin. Romans 6:1-3, because we are dead to sin, how can we keep living in sin? 1 Peter 2:1-3, we should not just believe in God, but crave pure spiritual milk, ridding ourselves of all sin for the opportunity to just taste a drop. Leviticus 11:45, "be holy, because I am holy." And there are so many more verses, again and again God telling us to stop sinning, that we should abandon everything that keeps us in chains on this earth and follow Jesus with all our heart, mind, and strength. I could continue to explain why we should stop sinning, but the answer is as simple as God hates sin, and as such we should also hate sin. There really isn't much more to say. Follow Jesus, and purge yourself of all false teachings and sinful lifestyles so that you may live like Jesus. Do not use our Father's grace as justification for sinning, but rely on his strength to help deliver you from temptation.