The concept of “social mortgage” is precisely that the desperately poor have a right to assistance, or the right to steal what they actually need. The civil law recognizes “necessity.” You may steal a neighbor’s hose to put out a fire. You may steal your neighbor’s car to take someone to the hospital.
Where in Scripture? Hmm.
The priests took the bread from the sanctuary to feed the starving. Jesus mentions this when he and the disciples are criticized for picking heads of wheat to eat on the Sabbath.
Can’t think of any other specific incident. But one can always consult common sense as well as Scripture.
You are arguing the thought of Aquinas, not Scripture. The Bible prohibits stealing and supports private property rights, whereas Aquinas essentially laid out a philosophical basis for theft heartily adopted by Rome.