Well there IS a randomness. Mutations themselves are not the children of necessity, but rather, are a lottery. Sometimes creatures will "hit the jackpot". Then the trait may or may not be successfully transferred to their young, because said trait has either made them more potent, or more virile, or more desirable, or more effective, etc. etc. It's a process that is invisible while it is happening and takes tens/hundreds/thousands of generations to produce substantial results on.
Example:
There is a species of hamsters. We'll call them Species A.
In the lowlands of a certain valley in the Gobi Desert, a group of Species A resides. This group is almost entirely blocked off geographically from other Species A hamsters. One day they are introduced to Bacteria X. It causes a fatal disease in hamsters. Many of the Species A are wiped out.
However, a few of the hamsters possess a gene mutation which makes them immune to the effects of Bacteria X. These hamsters live on, and reproduce. Eventually, after several generations, all the hamsters in this valley are immune to Bacteria X, because the ones who weren't, died.
They have now become Species B (or, Subspecies A... Won't get into that), because they have become genetically divergent from Species A as a whole.
Evolution isn't about necessity, but the products you see SEEM to produce that result. This is because you're seeing the end product of a test/fail/test/fail/test/fail/test/fail/test/fail cycle which has lasted millions of years. In the example, if none of the hamsters had been resistant to Bacteria X, then they all would have died, and that would have been it. It came down to luck.
People don't like to think of their coming into being as being the result of an immeasurable number of lucky draws. But I think it's extraordinary. The mere mathematical possibility of your reading this message at this point in time is so incredibly miniscule, it can almost be classified a miracle.
Perhaps God isn't so much a being, or a force. Perhaps it is a system of luck, a pattern, which has brought you, and our species, to where it is now. But that idea is probably too tenuous or insubstantial for people to consider.