Firstly, the Kalam cosmological argument doesn't state that there must be a point at which nothing existed, it simply states that there was a time before which there was no time (or space, or matter, or anything else actually.) And this is supported by the majority of astrophysicists and other scientists. Secondly, the idea of a timeless, spaceless, immaterial, incredibly powerful Being who has aseity does not jump to any conclusions. It can be deduced from the properties that must be assigned to whatever caused the universe, whether that was God or not. The only alternative to that would be that an abstract object caused the universe to exist, but that simply makes no sense because abstract objects simply have no causal properties.