Objection: this is just a God-of-the-gaps argument. Response: the Kalam provides POSITIVE evidence for what the cause is, not merely an appeal to ignorance.

God-of-the-gaps = we don't know, so God did it. The Kalam is different: it gives positive reasons to think the cause is a spaceless, timeless, immaterial, powerful, wise mind. It's argument to the best explanation, like identifying a murderer from fingerprints and death threats — not "Bob of the gaps."