Despite some of it being in the Bible, socialism and humanitarianism isn't on the agenda for the major Christian players. There are absolutely some churches that do great work in their communities, but that's tarnished by the bigger groups who use the power of religion to control the masses and are not interested in considering the softer sides of messages from Jesus.
And the US was founded by a mix of believers, with the intention of being secular for the protection of all beliefs. They knew first hand from history and their current situation what mixing religion and politics does, and also what drawing a line for some beliefs and not others does. Fighting about religion was often between sects of Christianity, and a secular protection helped everyone. It was idealistic, never was 100% and drifted a lot away from that goal, and how far it is seems to correlate with the problems we have.
If they sit down at the table with them, or allowed them to sit there, they are one.