Why is it so hard to conquer your demons? Probably because you have made friends with them. Evil does not present itself in all its repulsiveness, but in the form you most desire.
People make excuses for their failings, because they have already excused themselves. So, they rationalize everything which should be shunned. Then, they continue to do what they already wanted.
To progress, you must learn to deny yourself. If nothing good is born of it, then nothing good will come of it. Toss it in the garbage bin and spare it not even a backward glance.
This can be extremely difficult, because the evil resides within. You will cling to it, because it is all you ever wanted. And like a bad rash, it refuses to go away.
To be successful, you must come to reject it entirely. Evil is merely an absence of caring. Fill the holes in your soul and wickedness will have no place to lay its head.
When it is gone, seal all the entrances. Remember your failure and take steps to prevent a repeat performance. Anyone can fall, but it takes great courage to rise again.