In the land of the killers a sinner's mind is a sanctum
Similar idea to the phrase “in the land of the blind the one-eyed man is king”. In other words, having one eye isn’t ideal, but when surrounded by a bunch of blind people you are going to be thankful for what you have.
In this case, being a sinner isn’t ideal, but it is still the lesser of two evils when compared to a murderer. Normally the mind of a sinner would be thought of as a dark and dangerous place, but compared to the mind of a murderer it’s preferable.
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