If you truly believe this, then you should be more than supportive of someone who is voting in keeping with God's principles. It is a good thing for them to do personally, and God will ensure that whoever He wants in office will be there, regardless of that individual's vote.
Right?
The reason America should be strong and free is because it is a nation of mostly Christians and a nations where Christians can escape persecution abroad. It is also a nation that spreads the Gospel of Jesus throughout the world and feeds the poor and destitute mainly through private Christian donations and volunteers.