Pro 3:9 Honor the LORD with your possessions, And with the firstfruits of all your increase;..
It is the end of our being to honor God not only with our bodies and spirits which are His but with our estates too. We turn our blessings into praise and thanks by giving. This is what David meant when he chose not to offer to God a burnt offering that cost him nothing, (1Ch 21:24). To be clear, David was not trying to pay God back, his freewill gratitude was demonstrated by action. He wanted more than lip service.
Freewill offering or giving is the ability to act without the constraint of necessity. Psa 54:6 “With a freewill offering I will sacrifice to you; I will give thanks to your name, O LORD, for it is good.” Where riches increase we are tempted to honor ourselves, but the more God gives us the more we should study to honor Him. It is our duty to make our estate serviceable to our faith, advance His kingdom and do good to others in need. 2Co 9:10 “He who supplies seed to the sower and bread for food will supply and multiply your seed for sowing and increase the harvest of your righteousness.” God provides that we might have an opportunity and ability to help others especially believers. All the money, time, and resources we give to the church and support of others are to be freely given, as the Spirit leads. It is not about quantity but quality, the manner in which we give: for God loves a cheerful giver. A lake that has both inlet and outlet remains fresh. To God’s honor, we must have an outlet.