This is a matter of obedience. God has set forth specific instructions about tithing and making an offering. Malachi 3:10 says Bring the whole tithe into the storehouse, that there may be food in my house. Test me in this,” says the Lord Almighty, “and see if I will not throw open the floodgates of heaven and pour out so much blessing that there will not be room enough to store it.
Offerings are gifts given above and beyond the tithe. From a practical sense, tithes and offering are used to provide financial support needed for the church to function.