You have so little faith!

This may also be translated as, “You have so little faith in me!” or, “You do not trust me very much!”

Why did you not trust me to keep you safe?

Jesus uses a question to tell Peter that he should not have doubted. You can make explicit what Peter should not have doubted. Alternate translation: "you should not have doubted that I could keep you from sinking!" (See: rc://en/ta/man/translate/figs-rquestion, rc://en/ta/man/translate/figs-explicit)