Christians should live as Christians in a pagan world

Evangelization is always on my mind.How not to evangelize (unhelpful evangelization) (How should we evangelize?) But I think the thing we're forgetting is the different reasons people have for either 1) Leaving the Church. Which I have found is usually one of two reasons. 1) Misunderstanding of what the Church teaches, and 2) Justifying ones own sinful behaviour.
I don't want anyone to leave the Church, but I know that some people will. Let's talk about the second reason. (And, as to the first reason, please make more Catholic tracts available in Portuguese, thanks).
Many of us try to justify our own sinful behaviour. I am no exception. One thing positive about being baptized as an adult, is that I have already been forgiven of most of those sins, via baptism, (An overlooked passage on baptismal regeneration and infant baptism)  and the post baptismal sins, I have confession (John 20:23).
But, in a pagan age, with pagan morals, a Christian should stand out.
Besides, I've lived as a pagan (though I would not have called myself that). Paganism is empty, hollow, hedonistic, only living for onesself. Of course, you have the virtuous pagans of old, but once one has been enlightened by the light of Christ, he hasn't gotten a reason to be any sort of pagan, let alone, to live as one.
Of course, when the state religion is paganism, it's difficult to live as a Christian.
You may say, "Surely Charlie, you're talking about the Roman empire". No, I'm not.
Just to take an example, look at the United States, where I live.
We have, as a matter of state policy, genital mutilation.
We have, as a matter of state policy, promotion of baby murder.
Does this mean that we just accept this?
NO!
"For know you this and understand, that no fornicator, or unclean, or covetous person (which is serving idols), hath inheritance in the Kingdom of Christ and of God. Let no man deceive you with vain words. For because of of these things cometh the anger of God upon the children of unbelief. Be ye not therefore partakers with them. For you heretofore darkness, but now light in the Lord. Walk then as children of the light. For the fruit of the light is in all goodness, and justice, and truth; proving what is well and pleasing to God: And have no fellowship with the unfruitful works of darkness, but rather reprove them. For things the things that are done by them in secret, it is a shame to even speak of. But all things that are reproved, are made manifest by the light; for all that is made manifest is light. Wherefore he saith: Rise, thou that sleepest, and arise from the dead: and Christ shall enlighten thee". (Ephesians 5:5-14)
So, what should we do? Well, we should call sin, well, "sin". Don't worry about people throwing a single Bible verse about "not judging" (which is almost always quoted out of context, (Sometimes, we're supposed to judge)
How many people know that living with your boyfriend or girlfriend before marriage, under ordinary circumstances, is a sin? (Bishop Sheehan: Cohabitating Couples Live In 'Mortal Sin')
(Government promotion of this is part of the problem, seriously, ask co-habiting couples, it's usuaully justified by it being too expensive to be married, or, the absurd answer of not wanting to get divorced. Then you shouldn't be with that person).
Go to confession. Go to Mass/Divine Liturgy. Live a life of holiness. Bring the gospel to those who don't know it.
Be compassionate.
Be caring.
Be Christian.

*All verses are from the Douay Rheims version