The Bible teaches that there is an enemy of souls. Modern man in his so-called wisdom chooses not to believe in a personal devil.
The evidence showed itself once the crop began to grow. The effects of sin in the heart come to light gradually. The disease of sin is progressive. To begin with the tares lay hidden in the earth in the form of seed. If sin that should not have been there. A man or a woman may commit new sins at the end of their lives which they have not committed until then. We come into the world with fallen natures, but childhood is a relatively innocent time. The twisting and distortion of sin does not normally show itself in its true colours until character is fully formed and our hearts are further hardened.