If we're armed with all these external things, putting that out there, not looking inside and trusting what I am on the inside, then Satan can accuse till the cows come home. The way I often think about this is that the devil is telling us something that's true about us. He is preaching in a sense a gospel to us, but if we don't have a good understanding of the law and gospel distinction, then cursed are the ones who can't abide.