I was going back in my notebook to re-read something I had written the day after falling into sin. Actually, I don't know that I would consider it a "falling" - more of a running.
Sometimes I feel so powerless over sin once my mind gets running. It reminds me of the story I heard once (true story or not, the illustration is good)
I was told that the way Eskimos will get a wolf is they dip a big knife in deer blood, let it freeze, then do that over and over until they have made a "blood popsicle". Then they will pack the knife handle in the snow with the blade sticking out of the ground. Eventually a wolf will smell the blood, find the knife, and start licking the blood. By the time the wolf gets down to the blade, they are in such a frenzy, they are slicing their own tongue and do not realize that the blood they are now enjoying is their own.
That is an illustration of us in our sin. We can get worked into such a frenzy that we become blind to anything else. Blind to the consequences, nothing else matters in that moment. It is extremely scary to consider that God's Word warns repeatedly of a hardening of the heart, a giving over to sin. Imagine looking back on your life and saying, "yea, there was a time I believed in God, but I just don't any more - this life is it, so I am just going to do what I want, when I want." There are people that say that and are fully convinced in their mind they are right, they do not even realize they are suppressing the Truth in unrighteousness.