People (including friends, neighbors, strangers, girlfriends, and wives) don't care how much you know until they know how much you care.
Cheesy but true. For a lot of issues that have been politicized, polarized, or marginalized it's important to remember this principle not turn discussion into about being "right", in my humble opinion. Take the High Road and try to be a statesman and leader by finding common ground and showing how your beliefs furthers those common goals or at least do not infringe on her beliefs.
This- finding common ground and showing that you care- demands listening and actually understanding (if not necessarily agreeing) with their point of view. I think the worst thing you can do is resort to rhetoric because it makes it seem like you're a mindless tool spouting propaganda and that the same ought to work on her.
If you must engage in discussion, make sure it's actually a discussion and not you trying to find another avenue to preach from- people can smell that a mile away- you need to be willing to conceded points (or at least perspectives based on possibly faulty facts). If your mind isn't open, again, they'll know they're being brow beaten and will stonewall you. Who knows, you might come away actually acknowledging you've been wrong about some things... you might not, either, but if the possibility doesn't exist it's not a discussion.
In my life, it's about showing freedom and responsibility to be the most important things and as two things that go hand-in-hand and the women in my life see that I'm both (free and responsible), they happily endorse or willingly accept (or at least tolerate) my actions and beliefs. Going into conversations trying to "win" isn't going to help, but living a life that shows something of universal value is something few women are going to deny.