I hope you mean bathe and not shower!
A shower will terrify them. If you haven't bathed a cat before, here is how I do it, and it really is the safest way:
Bathing a cat-
1.Trim claws, take off only the tip don't cut the quick
2. Throw some dry towels in the dryer to cycle on low and stay warm
3.Get a deep bucket, put warm water in it, just enough to cover the cat's rear end.
4. Place kitty inside the bucket (cat will grip the top of the bucket with front claws, let him) Scruff his neck (gently) and using your other hand, get him wet (not his head though)
5. Once he is wet, add shampoo and gently scrub.
6. Place him in the sink or the tub on a towel, dump the water and rinse him off.
7. Dry him with warm towels
I bathe all my cats this way (when I bathe them) and the bucket helps them to stay calm as well as retain the warmth of the water.
You want to put a towel down in the sink or bathtub because nothing scares a kitty more than losing his balance on a slippery surface.