I know I'm late to the party...
1 In the beginning God created the heavens and the earth. 2 The earth was without form, and void; and darkness was on the face of the deep. And the Spirit of God was hovering over the face of the waters.
3 Then God said, “Let there be light”; and there was light. 4 And God saw the light, that it was good; and God divided the light from the darkness. 5 God called the light Day, and the darkness He called Night. So the evening and the morning were the first day.
Scientists, to be truthful, would have to admit they are dealing with timelessness when they try to explain the beginning of creation. Since they do not retain God in their knowledge, they must go to the utmost of their reasoning with proclamations like "5 billion years ago" or such, really, uncountable measures of time.
That's what I understand about how science tries to deal with the spiritual or eternal.
So, no: reason, without God, is foolishness and will arrive at foolish conclusions.
There's much I could say about the beginning (like "why" God created anything at all) but that is for another thread.