One founder of communism had no Jewish ancestry; the other was a baptized Christian.
Communism's two founders were not Jewish by religion: Friedrich Engels, co-author of The Communist Manifesto, came from a devoutly Protestant family with no Jewish ancestry, and Karl Marx was baptized a Christian as a child and wrote an essay attacking Jews as the embodiment of money and capitalism.
Marx's father converted from Judaism to Lutheranism around 1816–17; Karl was baptized into the Evangelical Lutheran Church in 1824 at age six and later became an atheist.
In "On the Jewish Question" (1843), Marx equated practical Judaism with "huckstering" and money.
Engels was raised Pietist Protestant in Barmen, had no Jewish background on either side of his family, and became a militant atheist as a young man.