God is generous and so he calls us to be as well. What we do with what God has given us shows the world where our hearts are at and helps proclaim the gospel. We want to glorify God with every area of our lives, and that includes what we do with our finances.
Malachi 3:10 : "Bring the whole tithe into the storehouse..."
Luke 6:38 : "Give, and it will be given to you."
Proverbs 3:9-10 : "Honor the Lord with your wealth, with the first fruits of all your crops; then your barns will be filled to overflowing."