A frequent misinterpretation of this verse is to assume John the Baptist was entirely ignorant or unrelated to Jesus, ignoring their familial connection as cousins and the broader context of John's Spirit-led recognition of Jesus at the baptism (John 1:32-34); instead, 'I knew him not' specifies John's lack of foreknowledge regarding Jesus' divine identity prior to the revelatory event, not a denial of acquaintance or prophetic mission, while some erroneously use it to question the reliability of John's testimony or suggest his baptism was merely ritualistic without messianic purpose.
John 1:31
King James Version (1769)
31 And I knew him not: but that he should be made manifest to Israel, therefore am I come baptizing with water.
John the Baptist declares that his lack of prior personal knowledge of Jesus' messianic identity was purposeful in God's plan, as his water baptism ministry served to publicly manifest or reveal Jesus as the Messiah to Israel, underscoring divine orchestration in preparing the nation for the Savior's arrival and highlighting the Baptist's role as the forerunner who points to Christ without drawing attention to himself.