The simple answer is we believe everything we have comes from God in the first place. We give because we believe God has entrusted us to be leaders for hope in our church and our community.
The Tithe is the first 10% we are commanded to give. An offering is anything above the tithe. We want to be generous in giving back to our church and our community just as God has been generous to us. That looks different for each person; but the Bible has proven over and over that you can't out-give God. He is faithful.