Rebellion vs Denial

Is it possible to explain why from the Talmudic standpoint, to know G-d and act in rebellion to His will is worse than to deny His existence altogether?

If a little child will call the president bad names – it might embarrass the parent in charge, but no action will be taken against him – since he is an ignorant kid and he doesn't know better. Same if a man who has no clue in wine tasting will say about a gourmet wine that it's not good – that will not be offensive, he doesn't know better. Alike for our case; a man that has no clue about Godliness and will mock G-d or rebel against him will not be dealt with harshly like a man that knows G-d and does the same, ignorance, in this case, may help.