It's highly controversial to assert that conservative Catholics are somehow in control of God's will, while those of us who support some socially liberal policies are misguided, basing that support on "man's understanding" and "our own opinion." As though the conservative Catholics were not also human beings, and their interpretation of biblical literature were not based on their "own opinion," and their human "understanding"! 

In fact, socially liberal policies draw much inspiration from Christian or biblical sources. And the interpretation of those sources is guided by reason (God's gift to human beings), the love of justice (a responsible, logical reaction to God's creating us as social animals), and very often charity too (the greatest of the theological virtues).