I have a problem with God as a first cause argument, it accepts natural explanations for everything in the universe since the big bang but introduces an explanatory block for cosmogony with the God based explanation.
There is no good reason to believe that there was a creative intelligence behind the formation of the universe, and it's arrogant to maintain anything other than proper agnosticism about how the universe formed until we have more knowledge.
The wonderful complexity of the biological world is entirely explicable through evolution, it removes intelligence from the process of design and crafts exquisite biological machines without any outside interference. We can't use biology to prove God, every beautiful thing in nature was generated by natural laws acting on regular matter with no anticipation or foresight towards humans (no intelligent designer or elan vital).
If we look at more fundamental issues such as the origins of matter, energy, and space-time (all questions of physics) I don't see a point where anybody can justify theological explanations. There are tricky and deep problems in physics, but these don't lend support for God based explanations, there is nothing supernatural about the universe itself so why introduce a magic wand at the big bang?
Positing God as a first cause explains nothing, and it closes the mind to potential naturalistic explanations for those big problems. It also suffers from the infinite regress of what created God, for which the answer that God is infinite and had no beginning might just as well apply to a naturalistic explanation that invokes some static universe or multiverse.
The other issue is what role God as a first cause serves people, if God starts the universe and then doesn't interfere then he might as well not exist. The deist and the atheist are in exactly the same position when it comes to living an ethical life, making sense of the world, and questioning claims of revelation. On the other hand the theist gets into a harder position because they must suppose God has created our enormous universe, let it run for 13.7 billion years, to produce one planet with one species in one particular place in which to give direct instructions about how to live their lives.
I find it far more plausible to accept that I live on an island of low entropy in a universe running towards heat death, that I exist because of a long chain of historical contingencies that make my existence vanishingly improbable, and that the universe is explicable through scientific investigation; current grand claims about knowing what created the universe should be seen as arrogant until proven innocent.