Is snake having Ratlers similar to deer having Antlers?

Very different. Some snakes evolved the rattle just to warn other animals not to step on them. Deer, on the other hand, evolved Antlers to engage in intraspecific contests, or at times antipredator actions.

Darwinists, are comfortable in the belief that reptiles preceded mammals. According to that way then rats should have been smart enough to grow deerlers and not get caught so easily. Oh what a pseudo web they weave.

No. A rattle is audial and horns a visual. You can't warn from a distance with something visual.

No