As an observant Jew, how do you feel about the fabrications Joe Smith made to Torah? Regardless of the parsing NAL offers to do on the verses added by Smith, what is the Jewish verdict of such additions to Torah ‘in these latter days?’
You really can't add anything to the Torah. The Torah is just the first 5 books, what you might call the Pentateuch. As I understand it, all the rest of the Tanakh, what you might call the old testiment, is commentary, of fairly equal rank to other commentaries (Mishna, Talmud etc). (We really don't have a cannon; what we have are texts that are accepted by tradition to varying degrees. For example, the Zoharic sages accept the Davidic Psalms as of almost equal value to Torah.) What happened at Sinai is the seminal event; the testimonies of every other generation since, whether prophets, sages, or rabbis, reduces to meditation, interpretation, and commentary on that event, trying to make sense of it, trying to figure out how to live our lives in light of it etc. So I'm not sure the Jews even have a verdict on Mormonism any more than they would have a verdict of any other gentile faith or tradition. I think the sages and rabbis would simply say that it isn't Jewish and leave it at that.
This would be my principle: can you keep all the mitzvot and not be a Jew? Yes. Of course. By extension, can you e.g. believe in Jesus and not be a Christian as it is articulated in the creeds and cannons? Yes. E.g. gnostics, Ebionites. This is not a slam against gnostics, Ebionites, or Mormons. Christians accept, in their own way and according to their own interpretation, the Mosaic law and tradition. But are Christians Jews? No, certainly not. So too the Mormons. They accept, in their own way and according to their own interpretation, the source texts of normative Christianity. But are they Christians? IMHO no, they are not. This doesn't mean that a Mormon should not be president or that Mormons are not going to heaven or anything like that. It just means that the one is not the other. All the rest would be commentary.
But are Christians Jews? No, certainly not. Some are; and the rest of us may disagree... ;^)
Romans 11:1-22
1. I ask then: Did God reject his people? By no means! I am an Israelite myself, a descendant of Abraham, from the tribe of Benjamin.
2. God did not reject his people, whom he foreknew. Don't you know what the Scripture says in the passage about Elijah--how he appealed to God against Israel:
3. "Lord, they have killed your prophets and torn down your altars; I am the only one left, and they are trying to kill me" ?
4. And what was God's answer to him? "I have reserved for myself seven thousand who have not bowed the knee to Baal."
5. So too, at the present time there is a remnant chosen by grace.
6. And if by grace, then it is no longer by works; if it were, grace would no longer be grace.
7. What then? What Israel sought so earnestly it did not obtain, but the elect did. The others were hardened,
8. as it is written: "God gave them a spirit of stupor, eyes so that they could not see and ears so that they could not hear, to this very day."
9. And David says: "May their table become a snare and a trap, a stumbling block and a retribution for them.
10. May their eyes be darkened so they cannot see, and their backs be bent forever."
11. Again I ask: Did they stumble so as to fall beyond recovery? Not at all! Rather, because of their transgression, salvation has come to the Gentiles to make Israel envious.
12. But if their transgression means riches for the world, and their loss means riches for the Gentiles, how much greater riches will their fullness bring!
13. I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I make much of my ministry
14. in the hope that I may somehow arouse my own people to envy and save some of them.
15. For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead?
16. If the part of the dough offered as firstfruits is holy, then the whole batch is holy; if the root is holy, so are the branches.
17. If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root,
18. do not boast over those branches. If you do, consider this: You do not support the root, but the root supports you.
19. You will say then, "Branches were broken off so that I could be grafted in."
20. Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but be afraid.
21. For if God did not spare the natural branches, he will not spare you either.
Galatians 3:28
There is neither Jew nor Greek, slave nor free, male nor female, for you are all one in Christ Jesus.