During Old Testament times a freewill offering was a completely voluntary offering. It was done in celebration of God out of thankfulness for what He has done for us, and for His people. And this is still the same for us today. However, the greatest freewill offering we can give our Creator is our hearts. We give our hearts to God through Christ Jesus our Lord and our faith in Him alone. And we do so with the utmost joy and celebration because of our love for Him.