Why was Abel accepted and Cain rejected? It has to do with faith.
One looked forward to the coming Redeemer, the one promised who would crush the head of the serpent.
The other put his trust in his own substance.
One was named "substance"; the other, "vanity".
But Jesus didn't come for the righteous. He came for the sinners. He came to call the wanderers home. He came to seek and save that which was lost.