The colonization of the US began for one of two reasons, sometimes - often even - for both. The first reason was financial, gold pretty much. The second was religion - tending to weird, fundamentalist, and communitarian. So, from the get-go a huge part of the American deal was all about a very deep and perverse kind of religious experience. In part seeing in the New World a chance to redo the Bible from the beginning, seeing the virgin American continent as the new Eden, and rising up to build the New Jerusalem, A Shining City on a Hill (and yes, they talked like that) --- well, let's just say with all that they had some visions going down.
In my rather poor understanding, the settling of Australia was basically Irish convicts, more Irish convicts, and still even more Irish convicts - America got religious nut jobs and big-wig financiers looking to make an easy buck. It's a very explosive mixture to say the least.