As far as Islamic Shari`ah is concerned, riba or taking interest on bank accounts is unlawful or haram because it is an increase of money made without any effort or trade. Actually, interest does not make life easier as some people may imagine. Islam encourages people to look for other ways of investing money.

Dr. Monzer Kahf, a prominent economist and counselor states: Interest definitely does not make life easier, in fact it destroys the economic future of people as you can see through all the financial crises that we are now witnessing in America.

This does not mean that financing is prohibited. Indeed, financing is useful and has its appropriate venues in Islam (remember Islam is a total way of life, not only Prayers in a mosque).
Financing can be provided through a deferred payment sale, leasing or venture capital. Financing through interest-based lending is the only thing that is prohibited because it is not always done to buy useful and appropriate goods and services and also because the loan does not create value; while its use for buying goods and services may or may not create value. Regardless, interest is due to the lender whether or not the use of the loan creates value, and thus, the payment of interest perpetrates injustice.
this is a brief answer, but if you would like more details you can search on the internet for Islamic finance and the prohibition of interest (called riba in Islamic terminology).