God is supposed to be SELF-SUFFICIENT i.e. it is part of the religious concept of God that He/She/It doesn't need to be caused by anything.
Most orthodox scientists/materialists cannot offer an equivalent - that is they can;t work back to a self-sufficient original cause because that would put them fair and square in God territory. They have to avoid the question, simply by asserting either that the cosmos originated out of nothing (how?) or that in some other way the causal circle can be completed (e.g. ideas of an infinite causal chain, possibly in a repeating cycle).
Now, you may fairly object to the God concept but I think you have to admit it is not the same as the scientist's "original" cause which itseld must be caused.
