I can't count the number of times of seen a variation of the meme below:
Even setting aside that the basic premise is an affront to one of the founding principles of our nation, Separation of Church and State, this is an incredibly self serving and idiotic view. All it really does is confirm that many Christians are willfully ignorant and/or self deluded. Christ, and therefore Christianity, is not a good source of comparison. At least not for for any self-respecting decent human being. If you have doubts about this characterization you really need to read/reread the Gospels and pay attention to what's actually there.
In Matthew 10:22-28 Jesus is a complete asshole to the non-Jews around him which he follows up latter in the same chapter 10:34-35 with an outright endorsement of divisiveness and intolerance.
Then there are some cute passages in Mark where he does in fact make a statement that I fail to see any other interpretation other than a big-ol Fuck-the Poor (Mark 14:3-7) which he also follows up with yet another endorsement of hate (Mark 14:26).
This, of course, pales in comparison to his Luke 19:27 command to his followers to round up all non-followers and commit mass murder.
Basically, criticizing Republicans on the gounds of not being "true" Christians is utter bullshit. Depending on your preferred interpretation you could argue that they are being good Christians by being utter bastards. Then again, if you need a horrendous work of fiction like the Bible to guide your behavior I have to assume you are a completely unethical moron.