It's the politicians who announce that they are Christians are the ones that you are identifying here and should be avoided at all costs.The main problem with Christians having a seat at the table is that for some reason, the Christians that make it in to politics are about as unlike Christ as you can get. Ask yourself "What would Jesus do?" and they'll likely do the opposite.
I'd be happy for proper Christians to be part of it. But we need more Bob Maguire types and fewer BA Santamaria types.