4  In regard to these, they think it strange that you do not run with them in the same flood of dissipation, speaking evil of you.
5  They will give an account to Him who is ready to judge the living and the dead.
6  For this reason the gospel was preached also to those who are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.
(1 Peter 4:4-6, NKJV)  

Those who are dead in their sins do not understand why someone would become a Christian and no longer join them in sin. The moral behavior of the Christian exposes their immorality. The unconverted react by trying to marginalize Christians by slander, lies and other malicious means. They intend to neutralize your godly influence. Do not succumb to their pressure! First, remember they will answer to God one day. God will right every wrong they do against you. Second, remember the very reason the gospel is preached is to save those who malign you. If you give in to their pressure and compromise your faith, you damage your influence for good and work against the purpose of the gospel. You cannot help save sinners by going back to sinning with them. Live so that others see your good works and glorify God. Do not yield to the peer pressure of sinners. Yielding is sin.