The really crucial issue, however, is that Obama does not seem to have a conversion story which explains how he quit being a Marxist. In the experience of me and others, being a Marxist is sort of like being in a religious cult. It ends up controlling what you do with your life, the friends you choose, the mentors you pick and the careers that make sense to you. I have a fairly detailed conversion story. I remember the exact moment when I first realized I was no longer a Marxist. Obama, however, does not seem to have a conversion story in his autobiography.
We know his parents and grandparents were ardent marxists. He acknowledges that Frank Marshall Davis, an active member of the party, was a key mentor for him as a teenager. He admits he hung out with radicals in college. Terrorists, Bill Ayers and Bernadine Dhorn, played critical roles for many years in his life. Ayers wrote his autobiography for him, got him his jobs, and launched his political career. Obama even joined a marxist political party while in Chicago.
If he stopped believing, it would have been an incredibly life-changing event. There doesn't appear to be any evidence that he did. Certainly, his policies as president don't give us any indication that he did.