As he moved up the ranks after Republican extremists systematically canceled comparatively more sane people like Tom Emmer, the radicals let it be known that Mike Johnson would have leeway on budgetary matters that Kevin McCarthy never had.
Why? Because Mike Johnson is a Christofascist like them. Because he agrees on the court tenet of mandatory Christian nationalism, he has the freedom to do anything else.
This is exactly how things work for Trump, who of course endorsed Johnson.