I have common ground with all of my friends (or else they wouldn't be my friends); however, there are always varying degrees of disagreement between us. For me, these disagreements are learning experiences... Life is much more interesting when one is surrounded by a diversity of opinion.
One thing that I have learned, which has made me able to maintain lasting friendships with people with extremely different political opinions, is that at the individual level, none of it matters... their vote will not decide an election and as a non-voter, neither will mine.