even if inflation theory did describe a CAUSE for "the big bang" in entirety, which it doesn, not even close, it does not addressed the origin of mass energy, how energy converted into mass, how all of the conceptual designs of particles came into being, and where all of the physical laws come from.
this is not an argument about "the god of the gaps", this is an argument that science is totally incapable of providing any kind of answers about metaphysics. and this has long been accepted, but recently forgotten, within the scientific field. the very first athiests made athiesm respectable by proving this fact, and thus making the topic of metaphysics completely out of bounds on the empirical level.