I thought about it and if I want to buy a house in Germany, there is nearly no way that you buy it without interest. The exception is when you are wealthy. I know that bank interest is haram and I heard that there are also Islamic banks from which you can buy a house. For example the house has a value of 100k and they sell it to you for 150k to 200k. But when I buy a house with interest it is exactly the same. The difference is, that I pay the money over several years. And in the end I have payed for both 150k to 200k. How is this any different?
Islamic law doesn't preclude anyone (i.e. banks) from providing a service (i.e. assistance in purchasing a house) and making a profit (i.e. 100k) therefrom. It only regulates the acceptable means by which one may do so.
Those who consume interest cannot stand except as one stands who is being beaten by Satan into insanity. That is because they say, "Trade is like interest." But Allah has permitted trade and has forbidden interest. So whoever has received an admonition from his Lord and desists may have what is past, and his affair rests with Allah . But whoever returns to it - those are the companions of the Fire; they will abide eternally therein.
Just because one bank can make as much profit by charging unacceptable interest as another bank can by a resale markup doesn't make them equatable: The one is still forbidden and the other is still permissible.
My teacher used to explain it with an analogy. Nikah and Zina have the same outcome (sexual desire fulfilled), but one is halal and one is haram. Meat sacrificed to idols and meat sacrificed in Allah's name are both the same in physical composition, but one is halal and one is haram. The end does not matter, the means of achieving it matter.