Today a reader asked if I thought it was "morally wrong for a Christian to be a democrat"? In reply I said:
God is not a Republican or a Democrat :>)
The bible teaches us some moral principles that are routinely broken by people who are members of every political party. Note, however, that people make moral decisions as individuals, not as parties. There is no Christian political party just as there is no Christian company, just individuals who follow Christ however imperfectly.
Just to look at just one issue, I disagree with the position on abortion taken by the Democrat party in their platform, but so do many Democrats. While I like many things the Libertarian party supports, I also disagree with them on abortion, as do some Libertarians. The Libertarians are more extreme than the Democrats on this issue. However I am convinced there are true Christians who are members of both parties.
Humans are not perfect, so it would be unreasonable to expect any group of humans to be perfect. I and many other Christians have chosen to work within the Republican party as we feel that on balance it offends less against what we see as the teachings of scripture than the Democrat party. Others disagree.
To be effective within the political arena in the USA you must work within either the Republican or the Democrat party. On the national and state levels third parties have zero power, so working within them is the same as disengaging from the political process. We have to work within one of the two major parties if we are to change anything in our country.
I would love nothing more than to have two good candidates to choose from for each office in September. Therefore I hope that those within the Democrat party manage to improve it. Meanwhile I will work for issues and candidates I believe in. At this point in time most of those candidates are Republicans.
I hope this clarifies where I am coming from.