If not the Big Bang, where does the cosmic microwave background come from?

We say it comes from the great light that was created on the first day, which is different from the sun and stars made on the fourth day. That light was very large, on the order of six hundred billion miles in radius, and it was stretched out along with the heavens, as all the 'stretched out the heavens' verses indicate. Most of that light was used to make the stars, and you can calculate, from the size of the great light and the number and size of the stars, that all the stars could come from it with some left over. That leftover light went to the rim of the universe, and that is the background radiation the big bangers mistake for a relic of the Big Bang. On top of it, at the boundary, there is water in the form of ice. This also explains why, if you shut off all the light from galaxies, stars, and quasars, over fifty percent of the light still remains; it came from that great light. The residual makes a very isotropic radiation of about 2.75 Kelvin, just above zero, which is what you would expect, and the water is ice at that temperature, so everything fits.