The Jehovah’s Witnesses teach that Michael the Archangel became Jesus who then later returned to being Michael the Archangel. But, this position has logical problems – and scriptural ones, as well.   First, here are quotes that show the position held by the Watchtower Bible and tract Society which says that Jesus is Michael the Archangel.

• “In the last book of the Bible, Revelation, the apostle John relates how Jesus, as Michael the archangel, defeats the Devil, (Watchtower 9/1/2011, p. 8, The World’s Secret Ruler Exposed).
• “So Michael the archangel is Jesus in his prehuman existence. After his resurrection and return to heaven, Jesus resumed his service as Michael, the chief angel, “to the glory of God the Father.” (Watchtower, 4/1/2010, p. 19, Is Jesus the Archangel Michael?)
• “These spirit sons of God have personality, divine qualities, and free will. They are superbly organized and have high positions in God’s arrangement, the archangel being Michael (Jesus’ heavenly name).” (Watchtower, 5/15/2009, p. 21 par. 2, The Angels—“Spirits for Public Service”).
• “The angel foremost in power and authority—the chief angel—is named Michael the archangel. (Jude 9) He is none other than Jesus Christ.” (Watchtower, 3/15/2007, p. 21 par. 4, Angels—How They Affect Mankind)

In Jehovah’s Witness theology Michael the Archangel became the man Jesus, who then became Michael the Archangel again. But there’s a problem. Let me explain.

Michael the Archangel is a living being who has characteristics consistent with being an angel. His “personhood” is tied up with his nature. Just as a human being’s personhood is tied up with his nature.

Personhood

When we speak of personhood we are talking about the quality of self-awareness, self-identity, having a will, emotions, etc.  Therefore, each human being is his own person and each angel likewise is his own person.

Nature

If we were to take a man and cut off his arms and his legs and blind him and make him deaf, is he still human? Yes, he is. This is because the essence of what makes someone human is not defined by physical attributes. There is an inner quality, an inner essence that makes a human being a human. Likewise, there is an inner quality, an inner essence that makes an angel, an angel.  But the nature of an angel and the nature of a human are not the same thing. They are completely different even though they can share similar characteristics such as being self-aware, having a will, emotions, etc.  Likewise, we are completely different in nature when compared to God, yet we also share characteristics similar to him in personhood such as self-awareness, having a will, emotions, etc.

In addition, the mind, personality, and personhood of a living, sentient being is tied to the nature of that being. So, if an angel were destroyed so as to not have existence, his personhood is also destroyed. He no longer has existence. In the case of the Jehovah’s Witnesses, when Michael the Archangel became a man, the angelic nature was destroyed because it was no longer in existence.  After all, the Jehovah’s Witnesses teach that the angel became human. But since being a human is not the same thing as being an angel, then logically the angelic nature had to cease to exist.  However, the Jehovah’s Witnesses say that the essence and personhood of Michael the Archangel was changed into that of a human being, and then later that same essence and personhood was changed back into an angel. But how can this be since a person’s identity and personhood is tied to the nature of what he is? If the nature ceases (Michael stopped being an angel), then the personhood of Michael ceased and could not become what it was not:  human.  Therefore, in the Jehovah’s Witness theology there is a loss of continuity of the personhood between Michael the Archangel became Jesus and who then became an angel again. Their position makes no sense and it cannot be true.