I'm a Christian, but I don't want the government enforcing my version of my lifestyle on everyone else. I respect their right to decide what is right for them, so long as it doesn't interfere with my right (or the right of anyone else) to do the same.
It's not the place of the government to engineer society. That's up to us, through our personal power of persuasion and the truths of our messages.
There are always conflicting rights, and any judgement of which should predominate in a given conflict is the critical factor in applying this principle.
The judgement of "which should predominate" by Libertarians often comes out with a result which echoes social liberalism.
Case in point: abortion.