Being in basic agreement on some moral standards does not equate to being Christian, nor is government called to spread the Gospel. This is not the biblical purpose of government, but to establish a peaceful state where it can be.
The Dems would competley undermine every aspect of that and are an enemy of Christ in toto, spun myriad ways to fool the world and confuse the church. They are indeed wolves in sheep's clothing, and far more cunning than you are admitting. This does not mean they can thwart God's purposes. In any case, the GOP is not called to be the body of Christ, and no Christian should think they are. As far as I know, no Christian does. Sharing moral standards is right for the purposes of government.