Hi Muck! The Founders Created the Congressional Chaplain and understood the importance of opening invocation before legislative sessions--which we've done since they created the Constitution.  They did so, as today, for meditation and guidance, and not to "force" anything, as you try to say.

While they have always been Christian, *guest chaplains* have included many faiths of invocation ( except,....Satan-worshippers).  Clearly, again, for the reasons already stated above. Hope this helps!