Millennials (and generations following) don't understand themselves. They are searching, aching for self-discovery and self-transformation. They don't see how the pendulum swung in a rejection of truth, when it was not truth's defect at all.
We are called to teach those who oppose themselves, but we’re not called to do it with virtual picket signs and pitchforks. We’re called to do it gently, patiently, and with meekness. After all, it’s God that will lead them to repentance and the acknowledgment of the truth, not your rhetorical skills.