Is believing you are doing the will of God (i.e., the Church) sufficient? Doesn't Christ answer this question when he says, "They will put you out of the ѕуηαgσgυєs: yea, the hour cometh, that whosoever killeth you, will think that he doth a service to God. And these things will they do to you; because they have not known the Father, nor me." (John 16:2-3). And just prior to this statement, He tells you that he is saying this so you won't be scandalized.
I have often told people just what these folks say above.