What is the ruling on consuming the money of banks and financial institutions in Christian countries and dealing with them?

It is not permissible to deal with usurious banks, whether through depositing or investing, regardless of whether they are in Islamic or non-Islamic countries. This is based on the Hadith: "The Prophet (peace be upon him) cursed the one who consumes usury, the one who pays it, its scribe, and its two witnesses, and he said: 'They are all alike.'" An exception to this is the case of necessity for placing money in a bank due to fear of theft. If one cannot find an Islamic bank, it is permissible to place it in a current account that does not accrue interest. If any interest is gained, one must dispose of it by giving it to the poor.

The majority of scholars are in consensus regarding the prohibition of usury in both Dar al-Islam (Abode of Islam) and Dar al-Kufr (Abode of Disbelief). However, Abu Hanifa held the view that it is permissible in Dar al-Harb (Abode of War) between a Muslim and the people of war. The majority relied on the generality of the evidence prohibiting usury and refuted Abu Hanifa's evidence by stating that "no usury" could be a prohibition, and that whoever enters Dar al-Harb with a guarantee of safety is not permitted to appropriate money through deception and theft.