Just to clarify: before the universe’s initial point is a concept that’s absurd. It’s like “north of the north pole”. No such beast exists.
Nothing, however, does exist in the form of the spatial vacuum. We think that space, in the empty universe (Milne Universe) has a definite physical property. Contrast that with the anything less than t=0 when there was no “spacetime”. That’s not really “nothing”. It’s “not even nothing”.
That said, there are cyclic models, ekpyrotic models, etc. which deal with the issues of how a self-consistent universe that has an ab initio point in space time could come to exist. This basically puts a rigorous “naturalistic” set of models on the table that are wholly without the need for theistic interpretation. Scientists are, on the whole, used to looking and seeing: that is, they’re used to believing in things for which there is scientific evidence. As it is, there isn’t scientific evidence one way or the other for God and the interpretative spin that is put on scientific discoveries by theists are basically as untestable from the get-go.
History seems to lend itself to comparisons. When Deism was first proposed as a solution to the discoveries of physics that made a supernatural deity obsolete in terms of most natural phenomenon (God was no longer required for rain or lightning or earthquakes, etc.), it was done in such a way as to preserve a non-obseverable nature to theism. This allowed for “practical atheism” of the scientist which didn’t have to worry about such things as God coming round and totally messing up experiments. One of the fundamental assumptions (that is, by the way, tested frequently) in science is that physical laws do not change depending upon time or place: there is a universality to them. If that’s the case, then “God” is not allowed to violate them which basically puts a damper on any omnipotence features you’d like to apply to her. That’s what made Deism clever because it offered God a way out of being confined by natural laws. God could have CREATED said laws and then sat back and watched it all unfold. A little neat bit of metaphysics, if you ask me.
So that, I think, is the answer to the OP. The reason there is a sort of atheism in the scientific community is because, in the practical application of science, atheism is what is used to actually do the work of science.
The thing is, there is a whole realm of unknowable things (metaphysics) which science doesn’t touch on. That’s the origin of theistic scientists. Fact is, a lot of scientists have their blinders on and don’t care about the metaphysics of situations. Those that do worry about such things (“those that think deep thoughts” as Freeman Dyson would say), often find themselves in the unfortunate position of treading on the toes of people who have spent their whole lives working out (maybe not rigorously) the ways metaphysics can work.
The dialog is not over, but as science becomes more and more descriptive, there will continue to be people who just don’t care about the things that are “unknowable”. They’ll stick to the solvable problems and leave the rest up to others.