One of the distinctive beliefs of the Jehovah’s Witnesses is their contention that Jesus and Michael are the same person(*). In JW Christology, Jesus pre-existed as Michael and now exists as the spiritually re-created archangel Michael (JW theology does not hold to a physical resurrection, so Christ/Michael is “only” a spirit). For a booklet providing an overview of what (and why) JWs believe what they do, see What does the Bible Really Teach, a booklet JWs pass out while engaging in their witnessing activities.
There are many responses to this Christology one can offer to the JWs one will encounter, whether at work or, more often than not, when they come to one’s door on a given Saturday. While I am critical of much of his Christology, Sir Anthony Buzzard presents a good discussion of the problems with the JW appeal to Michael being called a “prince” in Dan 10:21 as evidence for their theology here:
Moreover, such a Christology is at odds with the very first chapter of Hebrews, where the author (who I believe to be the author of Luke-Acts, not Paul) alludes to and quotes from a series of Old Testament texts in an attempt to prove, among other things, that Jesus is greater than any of the angels. As archangels (in my experience, JWs claim there is only one archangel, Michael, though I am not sure if that is “official” JW teaching) and angels are the same ontological class. In effect, JW Christology answers the questions the author of Hebrews claims there are no answers to and that the author was wrong in his assertions. Consider the following (quoting the JW’s very own New World Translation [NWT]):
For example, to which one of the angels did he ever say: "you are my son; I, today, have become your father"? And again: "I myself shall become his father, and he himself will become my son"? (Heb 1:5)
But when he again brings his Firstborn into the inhabited earth, he says: "And let all God's angels do obeisance to him." (1:6)
Also, with reference to the angels he says: "And he makes his angels spirits, and his public servants a flame of fire." But with reference to the Son: "God is your throne forever and ever, and the scepter of your kingdom is the scepter of uprightness." (1:7-8)
But with reference to which one of the angels has he ever said: "Sit at my right hand, until I place your enemies as a stool for your feet”? (1:12)
In these texts, Christ is presented as (1) distinct from all angels and (2) superior to all angels. To read them in the way that JW theology dictates makes the entire Christology and apologetic arguments of the author of Hebrews of the supremacy of the New Covenant over the Old to be internally inconsistent! One cannot engage in any meaningful exegesis of these texts and hold to a Christology that teaches Michael and Jesus are the same person. If any Latter-day Saint gets into a theological conservation with a JW acquaintance, they would do well to ask questions based on this issue to get them thinking about this central issue than "peripheral" issues such as the propriety of celebrating birthdays or blood transfusions.
(*) Some individuals and groups have associated Michael as a "Christophany" (OT appearance of the premortal Jesus), but such was/is interpreted within a Trinitarian framework (e.g. Charles H. Spurgeon). The JWs hold to an Arian Christology and interpret their identification of Jesus with Michael within that framework (e.g. non-eternal personal pre-existence), differentiating them from the Seventh Day Adventists who hold the "OT Christophany" view (at least from my, albeit limited, readings of SDA literature). So, unlike some other individuals and groups who make this association (and therefore hold that Jesus is ontologically "deity"/"God"), the JWs hold that Jesus is, ontologically, an angel.
(*) Some individuals and groups have associated Michael as a "Christophany" (OT appearance of the premortal Jesus), but such was/is interpreted within a Trinitarian framework (e.g. Charles H. Spurgeon). The JWs hold to an Arian Christology and interpret their identification of Jesus with Michael within that framework (e.g. non-eternal personal pre-existence), differentiating them from the Seventh Day Adventists who hold the "OT Christophany" view (at least from my, albeit limited, readings of SDA literature). So, unlike some other individuals and groups who make this association (and therefore hold that Jesus is ontologically "deity"/"God"), the JWs hold that Jesus is, ontologically, an angel.