For it is very difficult to argue that certain actions are morally wrong to people who reject absolute truth. Try arguing that 2+2=4 with a person who rejects the very notion of addition. Obviously, there is a need to inculcate a notion of absolute truth in a society which has rejected the concept. In the meantime, there is also a need to find alternate methods/arguments to combat moral problems.
And one method, quite simply, is to shine a bright light on the inner workings of immoral actions. Morally wrong actions or decisions, at their core, are disgusting on simple reflection. For example, contraception is also the practice of sticking rubber onto the most intimate places on the body or ingesting chemicals to "safely" engage in intimate acts and shut down natural biological functions.
Contraception is morally wrong – but that fact stops few from engaging in it. Many things are morally wrong (stealing, lying, etc.); that doesn’t stop people from doing them. Contraception's innate ickiness - few consider that element.
Emphasizing the innate nastiness of certain moral evils would go a long way towards the eradication (or at least the decrease) of those evils. Pornography is perhaps the most obvious instance where this strategy could be utilized. At least from an argumentative standpoint, the problem with porn isn’t that it is morally wrong, per se. The problem with porn is that it is an admission of cowardice and failure on the part of the user.
The solitary porn addict essentially admits that he or she isn’t man or woman enough for a real relationship. The male porn addict has only the cold computer screen to give him temporary relief from his sexual desires. The female porn addict admits that the only way she can attract those she desires is in her fantasies. Solitary porn is an admission of failure – the failure to be alluring, the failure to attract.
Couples that use porn to “spice up their sex lives” are no better. Essentially, they are saying by their porn usage that they take their cues from others to enjoy sex, without discovering the joys of the act on their own. It’s like a twisted and more harmful version of adopting mannerisms and speech from movies; imagine a woman whose small talk consisted solely of Star Wars quotes.
Yes, morality should be inculcated. But due to our fallen human nature, humans are rarely influenced solely by moral concerns; few humans are reachable solely through reason. Christians seeking a moral society should appeal to the heart and to the head; to the gag reflex and to the conscience.