God has accepted us because of our union with Him. So if we give our tithes under Moses' law to get approval from God, we will be operating in the dispensation of Law, the wrong dispensation. No, He already had you. Our giving provides a means whereby we receive a greater measure back according to what measure we mete out to others, that's all it is. When we preach with a 'getting mentality', it's because we're greedy.
All businessmen sow or invest to get a return on their money.
God already knows you're His by the birthing. No amount of giving or lack of it on our part can change that fact. So our giving is not one of getting. It's a giving out of love, because love gives and love cannot help itself but to be touched by the feelings of people's infirmities. That's the right motive.