The world cannot be relied on to fight evil for it is evil. Evil fighting evil begets more evil. The world is fickle and its foundations are on the shifting sands of humanistic morality. Its ultimate aim is to make society "better", not fight evil for the evil that it truly is.
Less than 10 years ago, general society, including many secular people would condemn homosexuality on moral grounds. A person suspected of being homosexual would be gossiped about at school and hated by even the wicked "TC" students. Now, after much, propaganda from the media, academia and political arena, only the bravest and most courageous of souls would speak up against the morality of homosexuality.
Why does the modern church only selectively fight against sex slavery? It is because it seeks the approval of people. Sex slavery is loudly condemned by the world and condemning sex slavery is praised as a virtuous act by the world. However, the world does not condemn sex slavery because it offends God. By no means! Rather, it condemns it only because it is politically correct to do so - that is, approved by the majority because it panders to their wicked human thoughts.
The world hates sex slavery because it violates the world's ethic of licentiousness and sexual immorality. It violates the false ethic of consent - that only consent between two adults matters regarding sexual activities and sexual relations. It is not because sex slavery is immoral per se that it is against it.
Just as the Enlightenment philosophers who opposed to slavery, disapproved of slavery on the grounds of its negative consequences of society, the world is against sex slavery on the grounds of its negative consequences of society. Such is the hypocrisy of the world, which loves to condemn religious hypocrisy while yet redefining its own hypocrisy as something other than hypocrisy.
The modern church even thinks that prostitution, the facilitator of sex slavery, should not be abolished, but rather regulated. What can be more foolish than that! To regulate something means that the thing being regulated is legal. Thus, to support regulation is to support the thing being legal. If the government made paedophilia legal or rape legal, would you support regulation? No! Of course you wouldn't! You would seek its abolition. For those Christians who support regulation of prostitution, why then do you support regulation of prostitution if you are opposed to the very thing which feeds on prostitution and is legitimised by prostitution? It is not hypocrisy on your part to support regulation of prostitution, but yet abolition of murder (except in abortion), paedophilia and rape?
The inconsistency and hypocrisy of many in the church regarding evils of fight against is blatant. This is the result of pandering to the ways of the world and its thinking. Such is spiritual adultery. Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God (James 4:4). The spirit behind spiritual adultery of the church is mammon. Mammon is the spirit which tempts the church into earthliness including earthly thinking. Why would he not want to tempt the church, for only the true church can truly fight evil for it is the only one that is full of light that the world can see?
The church must renounce all its temptations to succumb to serving mammon to shine as salt and light. Judgement starts at the House of God. For the time is come that judgment must begin at the house of God: and if it first begin at us, what shall the end be of them that obey not the gospel of God? (1 Peter 4:17).