The Kalam Cosmological argument.

[BrianSoddingBoru4]

I don't believe the universe began to exist.

Ok, then. Question to you: What existed 100 BN years ago?

a) Nothing. And if so, then everything came from nothing.
b) Nothing material, i.e. an Immaterial Spiritual Being.

Atheism is forced to hold on to a. Defenders of Kalam say b.

We know the Universe began to exist because we know its finite age.

Whereas the God of Christian Revelation has always declared Himself Eternal.

It is not obvious that premises 1 and 2 true are correct, therefore conclusions 3 and 4 are invalid.

Insufficient. It's insufficient for Atheists to claim "it's not obvious". They must show that the negation of 1 or 2 are more probably true, and then construct a logical argument of their own, if they want us to believe the Universe either did not begin to exist, or that what begins to exist pops into being uncaused.

Dr. Craig, the Athanasius of this age against the Arianism that is Atheism, has a put a lot of thought into this argument he popularized, and it stands imho.

You have it exactly backwards. Since you are the one promoting the argument, the onus is on you to demonstrate that the premise(s) are true, or at least reasonable, in order for the conclusions to be valid. Since there is evidence for acausality (radioactive decay, subatomic particles), you haven’t done so.

Implying that the argument is valid - even in part - because Craig thinks well of it is fallacious (argument from authority).

Boru