The Bible teaches that, as they are able, Christians are to help persons who are in real need and to refrain from charging interest in such situations. We should love our neighbor and not take advantage of his financial difficulties. Jesus says, "Give to him who asks you, and from him who wants to borrow from you do not turn away" (Matthew 5:42).
The Old Testament equivalent of this occurs in Leviticus 25:35-38:
If one of your brethren becomes poor, and falls into poverty among you, then you shall help him, like a stranger or a sojourner, that he may live with you. Take no usury or interest from him; but fear your God, that your brother may live with you. You shall not lend him your money for usury, nor lend him your food at a profit. 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.
The general principle that arises from these scriptures is that we should not exploit the poor in his distress. Solomon writes: "Do not rob the poor because he is poor, nor oppress the afflicted at the gate; for the LORD will plead their cause, and plunder the soul of those who plunder them" (Proverbs 22:22-23). By charging interest, we are in effect deepening his debt and making him weaker and poorer in the process. We should follow the Golden Rule, considering how we would feel were the situation reversed. Remember that part of the model prayer is "forgive us our debts, as we forgive our debtors" (Matthew 6:12).
Although a Christian's attitude should be one of giving, sharing, and helping in meeting the needs of the less fortunate, there are instances when it it is permissible to accept interest. For example, if money is loaned to another individual purely as a business deal so he can make money, then it is not wrong to collect interest, because both parties are sharing in the profits. It is also proper to accept interest from money placed in savings accounts, since the money is earning the increase. The interest is in no way hurting anyone else.