"And all the tithe of the land, whether of the seed of the land, or of the fruit of the tree, is the Lord's: it is holy unto the Lord."
Bbiblical scholars will argue that the obligation to tithe is for the Israelites only. In fact, giving 10% of your income is not even mentioned once in the New Testament. When Christ died on the cross, his sacrifice made the 10% tithe obsolete. But what about offerings?