Well, about two months back I decided to finally read the Bible all the way through, front to back. It’s interesting the stuff one finds.
The bit on Usary I was referring to is in the section of Exodus where we have Moses laying out the laws and rules for the Jews, as conveyed to him by God. In 22-25, it says “If you lend money to any of my people, to the poor among you, you are not to act as creditor to him - you shall not charge interest.”
Then there is also another section on it in Leviticus - again, where we have Moses laying down the laws of God. In 25-27 it says “Now, in case a countryman of yours becomes poor and his means with regard to you falter, then you are to sustain him, like a stranger or a sojourner, that he may live with you. Do not take usurious interest from him, but revere your God, that your countryman may live with you. You shall not give him your silver at interest, nor your food for gain. I am the Lord your God, who brought you out of the land of Egypt to give you the land of Canaan and to be your God.”
There might very well be more in the Old Testament, past the point where I’ve read to, or in the New Testament (as gghd mentioned). Now, whether or not this is meant to apply only to those who are, as you put it, God’s family, isn’t clear, though considering the rest of sections those quotes where in, I’d wager you’re correct. But even so, roughly 77% of the US is Christian or Jewish.
The old Catholic encyclopaedia has an interesting entry on usury: http://www.newadvent.org/cathen/15235c.htm
It traces its history from ancient times and in various cultures.
The entry refers to the OT passages you cite as only applicable to the Jews, and also states that the NT is silent on the issue.
Interestingly, the Church was fairly silent regarding the subject until the Middle Ages, when it was legally prohibited, but not dogmatically so. Ironically, the Jews were exempted from this prohibition.