This remark appears in the form of a question to emphasize Jesus' words to Philip. AT: "You really should believe ... in me." (See: [[rc://en/ta/man/translate/figs-rquestion]])
This is an idiom that means God the Father and Jesus have a unique relationship. AT: "I am one with the Father, and the Father is one with me" or "my Father and I are just as though we were one" (See: [[rc://en/ta/man/translate/figs-idiom]])