“Return to me, and I will return to you, says the LORD Almighty.” (Malachi 3:7)
I will send my messenger, who will prepare the way before me. Then suddenly the Lord you are seeking will come to his temple; the messenger of the covenant, whom you desire, will come, says the LORD Almighty. But who can endure the day of his coming? Who can stand when he appears? For he will be like a refiner's fire or a launderer's soap. He will sit as a refiner and purifier of silver; he will purify the Levites. Then the LORD will have men who will bring offerings in righteousness. Return to me, and I will return to you, says the LORD Almighty. But you ask, 'How are we to return?' Will a mere mortal rob God? Yet you rob me. Bring the whole tithe into the storehouse. 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.
The Catechism identifies the messenger who prepares the way as the figure of John the Baptist (CCC 719).
Brothers and sisters, test me in this. God rarely issues such a direct invitation to put him to the test. In the matter of the tithe, of the whole offering held back from the storehouse, God says: try it. See if I do not open the floodgates. The boldness of the invitation matches the boldness of the promise. The God who says test me has already decided what the test will prove.
Lord God, we return to you. You promised to return to us. Open the floodgates of heaven over your returning people. Through Christ our Lord. Amen.