The Godless Logic of Self-Interest
The 'if' statements of the Bible are designed to make us think about the logic we use to justify our beliefs and lifestyle. Jesus stirred His trainee apostles to think about why they were kind to people by suggesting that they had the morality of prostitutes ('sinners'). Such people were known to give people what they paid for, love those who loved them, show kindness to kind people, and lend as long as they would be repaid.