Paul is continuing the instruction of giving to the poor, suffering believers in Judea that he started in chapter 8. The principle that when I give to the poor, God supplies me back and increases my money and makes me more profitable is introduced (12). This is true. Yet, not all the time is it applied correctly.
What I mean is this: the believers in Judea were poor. The Gentile believers had money. Does that mean that the Judeans did not have faith in Jesus or that God was not pleased with them and their giving? No. Does this mean that God was happier with the Gentiles and their giving? No.
Jesus was poor, and he is the Son of God. The apostles were poor, handpicked by Jesus, and God performed miracles through them. My faith should not be measured by my wealth. If this were a true measure, then Caesar and Hitler were blessed more than everyone. They were not. They were evil.
I should not give to the poor as a measure of my spirituality nor as a financial investment (6-7). I have heard messages that present these false beliefs. Rather, I should give lovingly because someone is in need. I am to be happy to help, and I should not be concerned that God won’t meet my needs too.

