There’s a lot to talk about here regarding supposed Christian politicians. We could start with the separation of church and state. The founding fathers had seen the problems that come with a government heavily influenced by religion in England, and so they devised a government that purposely kept the two entities “church” and “state” separate. I also recall Jesus commanding his followers to make no oath to anything or anyone but Him. Seems to me that a true Christian would see a conflict of interest in following Jesus and being a politician.
And it wasn’t just in England where this was a problem. The American colonies had some serious growing pains as well. The first colonies in America were governed by church folks, mostly divided between Catholics and Protestants. If you happened to be a Catholic in a Protestant colony, or vice versa, you’d either be forced to convert, or if you refused that, they’d burn you at the stake for being a heretic. Things just get ugly when religion begins influencing politics. And if you think such things could not happen today, just consider the Taliban, and what they are up to these days, beheadings and all.