Hebrews 2:14, 17

Therefore, since [these His] children share in flesh and blood [the physical nature of mankind], He Himself in a similar manner also shared in the same [physical nature, but without sin], so that through [experiencing] death He might make powerless (ineffective, impotent) him who had the power of death—that is, the devil

Therefore, it was essential that He had to be made like His brothers (mankind) in every respect, so that He might [by experience] become a merciful and faithful High Priest in things related to God, to make atonement (propitiation) for the people’s sins [thereby wiping away the sin, satisfying divine justice, and providing a way of reconciliation between God and mankind].