Assuming you want to have a serious discussion... if anything, liberalism should be the default American position. Our very existence went against the conservative view of the day.
The reason I vote Democratic is that I see a clear divide between the interests of the Investor Class and the Working Class. And the Republicans will take the side of the investor class every single time.
Although I am a white, straight, cisgendered male, I don't see any good reason why people who aren't in that slice of the demographic should be treated any worse than I am, but that's often not the case.
Final point, the GOP panders to the worst in religious zealotry. If your religion makes YOU a better person, then by all means, keep doing that. When you try to impose it on the rest of us, we are going to have a problem.