Luke 1:4 - Ellicott's Commentary On The Whole Bible

Wherein thou hast been instructed. — The verb used is that from which are formed the words “catechise,” “catechumen.” &c., and implies oral teaching — in its later sense, teaching preparatory to baptism. The passage is important as showing that such instruction mainly turned on the facts of our Lord’s life, death, and resurrection, and on the records of His teaching.