I think that’s why Catholics need to Magisterium to discern these issues for you. There is enough common truth for the Magisterium to embrace Protestants as separated siblings based on doctrine alone. Within Mormon doctrine, there is not enough truth in official Mormon doctrine for Catholics and Protestants to embrace Mormons as Christian siblings. Zee is quite the staunch Mormon who is preaching the Mormon gospel on Catholic Answers. Therefore, you cannot embrace Zee as a brother in Christ. That’s all that I am saying. I have no idea how you made the determination that Zee is a follower of Chrsit. I would say that Zee follows the Mormon Jesus which is the different Jesus than then the One we know. Do you believe Muslims to follow Jesus Christ too based on the official Islamic doctrine about Jesus according to the Quran? We believe in the historic Jesus defined within the historic creeds and the Holy Scripture. That is the One True Jesus in which Mormons and Muslims reject.
I know you think you are loving your neighbor by embracing Zee as a brother in Christ. But the truth is that you are being unloving and unkind by making Zee the staunch Mormon your Christian sibling. He is in a very perilous condition, and needs to repent of his sin for embracing the Mormon gospel and the Mormon Jesus. As a sinner in emity with God, Zee needs to repent of Mormonism and turn from it to historic Christianity to find the historic living Jesus Christ who saves sinners from their sins.
Paul was writing about false apostles which is applicable to false prophets like Joesh Smith.
2 Corinthians 11
Paul and the False Apostles
I wish you would bear with me in a little foolishness. Do bear with me! For I feel a divine jealousy for you, since I betrothed you to one husband, to present you as a pure virgin to Christ. But I am afraid that as the serpent deceived Eve by his cunning, your thoughts will be led astray from a sincere and pure devotion to Christ. For if someone comes and proclaims another Jesus than the one we proclaimed, or if you receive a different spirit from the one you received, or if you accept a different gospel from the one you accepted, you put up with it readily enough. Indeed, I consider that I am not in the least inferior to these super-apostles. Even if I am unskilled in speaking, I am not so in knowledge; indeed, in every way we have made this plain to you in all things.
Or did I commit a sin in humbling myself so that you might be exalted, because I preached God’s gospel to you free of charge? I robbed other churches by accepting support from them in order to serve you. And when I was with you and was in need, I did not burden anyone, for the brothers who came from Macedonia supplied my need. So I refrained and will refrain from burdening you in any way. As the truth of Christ is in me, this boasting of mine will not be silenced in the regions of Achaia. And why? Because I do not love you? God knows I do!
And what I do I will continue to do, in order to undermine the claim of those who would like to claim that in their boasted mission they work on the same terms as we do. For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ. And no wonder, for even Satan disguises himself as an angel of light. So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
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The Mormon Jesus does not save because he does not exist.