Conversation so far:
What are the lyrics?
Both versions of the song open with the protagonist kneeling at a crossroads to ask God's mercy.
What happens after he asks?
The song has been used to perpetuate the myth of Johnson selling his soul to the Devil for his musical ability.

Question: What does he say in the song to give this idea?
Self-contained rewrite: What does Johnson say in the song to give the idea of selling his soul to the Devil?