This can be stated in active form. Alternate translation: "What kind of baptism did you receive?" (See: [[rc://en/ta/man/translate/figs-activepassive]])
You can translate this as a complete sentence. Alternate translation: "We were baptized into John's baptism" or "We received the kind of baptism about which John taught" (See: [[rc://en/ta/man/translate/figs-ellipsis]])