Let's be clear: Evolution is what we all see: That different animals such as dinosaurs, and different species of mammals and insects, existed in eras gone by at different periods.
Darwin's theory of Natural Selection is one among many to explain why we find the evidence of evolution, and is by far the most scientifically accepted such theory.

If by 'monster' you mean a step-wise change in an animal that then is either 'accepted' or 'rejected' by whether it survives or does not survive in nature, the common term in use is: mutation.

AS to whether or not one can put a value of chance on such occurrences, it depends on how you put together your initial conditions. All the declarations on how rare it would be for life to occur 'randomly' either are not very well defined, or indicate that life is a rare occurrence in the known universe, which complies with existing knowldge.

A common misperception of evolutionary theory is that somehow we (life) are becoming more advanced, or that there is some predestination in which some intelligent handsome creatures such as ourselves are the logical 'result'. This is the rankest of anthropomorphic attitudes.

We are simply the latest thing to come along, at best we are an intermediate form along the journey of time.

There is no biblical denial here. We are the latest of God' experiments. God will know when He's done, not us.

The main conflict between the religious and the scientific is lack of humility on the part of both sides.