The mistake these naturalists make is to reify the initial thesis: That there corresponds to human nature as such a natural end naturally attainable. The naturalists forget that in fact God has intervened in human history and calls all men to holiness (Vatican II, summing up Christianity). Thus, God offers us one end. Fail that end, we have failed everything. If by natural law we are oriented towards the obedience to God, then when God speaks (reveals himself) we must obey him. Otherwise, we give the lie about our “natural righteousness”. Since right now God is knocking on the heart of every man alive, Christians who believe this are called to witness to it to the ends of the earth. Who is a Christian to set limits on the grace of God? For why do I take prudential measures not to speak of God to someone might seem to be opposed to the Gospel? Is it for love of this man who is presently indisposed? Or is it, perhaps, my desire to have tea with him and enjoy his humor without being put in the awkward situation of having something disagreeable between us emerge? Perhaps it is such a human, too human, desire which keeps me from mentioning the Holy Name. “We could just have tea, agree on certain natural precepts, and leave it at that. I would go home. He would go home. End of the day. Tomorrow another day. What a good man he is!” In short, human respect and love of vanities are keeping me.
What do we prize more for this friend of ours? That he achieve another precept of natural law? Or that he be cut to the quick, realize the vanity of his show, find the foundation in Christ, and build thereon? But of course, the time and labor and warfare it shall take for him to be cut to the quick and then find the foundation is massive. All the while, he and I shall not share tea. He might consider me an enemy. A nuisance. Strange. Alien. So, I go on loving him and our teas, while he knows not where he is going. Nor can he be saved until he comes to faith. And what shall I say to the Terrifying Judge when he comes with his Angels to root out the wicked utterly and to spew out the lukewarm like vomit?