they're not charging u interest!!!they wanted to gain some profit...its not like u borrowing money...juz like dis:

1) u wanna buy a house.
2) u ask for islamic banking.
3) they'll pay for u first (they give money to u to pay, juz like u're the third party)
4) they sell it back to u.
5) like every item in the world, the maximum profit i would like is 50% ( but islamic banking is juz too kind)
6) finally, u have to buy the house from the islamic banking actually, not from the dealer.