Wow - I never heard of a Marxist Mormon before - I'm glad your friend felt accepted and free from pressure.
You've never heard of Joseph Smith?
"And they had all things common among them; therefore there were not rich and poor, bond and free, but they were all made free, and partakers of the heavenly gift. . . . Neither were there Lamanites, nor any manner of -ites; but they were in one, the children of Christ, and heirs to the kingdom of God." (
4 Nephi 1:3,17)
"But it is not given that one man should possess that which is above another, wherefore the world lieth in sin." (
D&C 49:20)
"Nevertheless, inasmuch as they receive more than is needful for their necessities and their wants, it shall be given into my storehouse." (
D&C 70:7)
"And you are to be equal, or in other words, you are to have equal claims on the properties, for the benefit of managing the concerns of your stewardships, every man according to his wants and his needs, inasmuch as his wants are just — and all this for the benefit of the church of the living God, that every man may improve upon his talent, that every man may gain other talents, yea, even an hundred fold, to be cast into the Lord’s storehouse, to become the common property of the whole church — every man seeking the interest of his neighbor, and doing all things with an eye single to the glory of God." (
D&C 82:17-19)
Of course, Joseph Smith lived before Marx, so he couldn't be a Marxist. And of course, these words came through Joseph Smith rather than from Joseph Smith. It's possible that he personally disagreed with them.
Nevertheless, there's good scriptural justification for any member of the Church to believe in the fundamental Marxist principle: "From each according to his ability, to each according to his needs!"