Possibly breaking "the biggie" by visiting numerous shinto/buddhist temples while in Japan, performing the water purification ceremony (Jewish -- really -- hold ladle in left hand, pour on right, hold ladle in right, pour over left, pretend to take a sip but not really), occasionally throwing coins in the charity box, clapping twice and bowing. Since my return, I've been violently ill for months withe a mystery illness, so I also must atone for thinking of myself as somehow important enough that G-d is punishing me. I'm agnostic (for which I also must atone) despite a desire to believe that is weaker than my capacity for rational thought, but I really am afraid I willfully committed idolotry and am being punished.