My general perspective is that modern Christian evangelism should (probably) focus on addressing the alienation of modern man, rather than on ethical issues - that what requires emphasis is the mystical, existential, even metaphysical aspect of Christianity, with sin conceptualized as being turned-away-from God rather than as a list of rules.
And the Christian mystical perspective being described not in terms of what makes you happy, but what is real and therefore productive of meaning, purpose and relation with the universe.
For instance, that when an orthodox Christian looks at the stars he knows that the Heavens declare the glory of God and the firmament sheweth his handiwork;
whereas for a secular modern like Calvin (of Calvin and Hobbes) the stars induce the cry:
"I'M SIGNIFICANT... screamed the dust speck."
This cartoon perfectly encapsulates the overweening spiritual pride and underlying utter nihilism of modern, secular man.
I was led to this idea of focusing on the mystical partly my my own response, when an atheist, to Christian ethical teaching.
Not by its own choice, Christianity has been brought into conflict with the modern world primarily on matters of sexuality and reproduction.
Naturally, therefore, among-ourselves, Christians must say NO to many things which the modern world first tolerates then encourages.
And this can be done rigorously, and through argument, since Christians share a belief in both natural law and revelation.
(Natural law being the spontaneous, instinctive human morality and spirituality - common to mankind).
Yet, the fact the Christians must strive to resist modern sexual and reproductive ethics in their internal operations, does not mean that this can effectively be done in the social arena.
It is precisely the triumph of modernity that in the social arena there is no belief in, indeed denial of, not just Christian revelation, but even natural law.
Without even a common basis in natural law, how can specific matters of sexual and reproductive ethics be discussed from a Christian perspective?
The answer is sexual and reproductive ethics cannot now be discussed from a Christian perspective - but only from a secular and hedonic perspective, concerned with this worldly individual happiness and misery.
Yet to discuss sexual and reproductive ethics from the perspective of what makes people happy or miserable, is precisely to reinforce the secular hedonic perspective.
Even if a Christian were to prove that, say, easy divorce usually led to misery - he could never prove that it always and necessarily led to misery, and the very act of evaluating in terms of here and now misery (or happiness) is precisely the evaluation used by the secular modern world; and precisely not the primary evaluation of Christianity.
So Christians can merely say what they believe (answer NO whenever the matter comes-up), stick to what they believe (still say NO even when persuasion or coercion is brought to bear); yet decline to explain their sexual and reproductive ethics in terms of secular hedonism
- simply to state that this is how things are from a Christian perspective; in light of natural law and revelation.
This is, of course, how other and non-native religions always have behaved in The West when trying to hold-out against pressure - not explaining; but instead saying, in effect 'it is not our custom', we cannot comply, we are commanded to refuse this.
And this has indeed proved far more effective than trying to fight coercion using the enemy's weapons.
In sum, Christians need to internalize that we are living in an alien culture which cannot understand us.
When resisting that alien culture, there is therefore no way to explain the true reason for resistance; merely the fact of it.
Those who truly want to understand must first become Christian.