God would have us live as His own sacred possession, separate from this world-system, but godliness is out of style these days. Religious leaders in ever greater number are telling us that to win the world we must become part of it and to win the people of the world we must fellowship with them in the things they do and the places to which they go. But the believer cannot impress the world by conforming to it. And even if he could this approach would still be contrary to the Will of God, for His Word exhorts us:
“Be not conformed to this world, but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable and perfect, will of God” (Rom. 12:2).
It is true godliness, consistent separation to God from this world, which most deeply impresses the lost to whom we bear witness.
True godliness exerts enormous spiritual power. It causes men to sacrifice—to suffer and die for Christ and for others. It exerts a profound influence upon those with whom it comes into contact. A truly godly believer will win the respect of other believers and by his example encourage them to live godly lives, while at the same time his godliness will convict the lost, so that they will either be angered or will turn to Christ for salvation.
This is why II Tim. 3:12 says: “Yea, and all that will live godly in Christ Jesus shall suffer persecution.” Carnal Christians do not like to think about the word “all” in this passage, but it is there and stands as a rebuke to their lack of consecration to God. They have “a form of godliness” but deny “the power thereof” (II Tim. 3:5). source