The belief was common to Arian Restorationist groups in the 19th century, and it is contrary to Scripture, indeed even the name of St. Michael indicares his status as not Christ, for Christ is referred to as “Emanuel” - God With Us, and “Jesus” an Hellenization of the Hebrew Joshua and the Aramaic Yeshua meaning “YHWH Saves” - proof of his deity. Christ is not an angel, since all angels are creatures, and are pneumatic.
The epistle of St. Jude, which is canonical inspired scripture, further confirms our Lord’s status, and unlike the Pauline epistles, which some try to negate using 2 Peter 2:16 to shoot down any interpretation which differs from theirs, lacks any means for eisegetes to try to refute it.