Q: I am considering opening up a business that manufactures coffins. Is it permissible as a Muslim to run this business? Am I right in assuming the same response could be used for running a taxi business that would commute people to church?
A:It will be permissible to manufacture and sell coffins, because the coffin itself is not haraam. There are times when a Muslim may be buried in a coffin; for example, if the ground in the cemetery is extremely soft and the grave keeps on collapsing; or the ground is very soggy and wet. Under these circumstances a coffin is allowed.
From this you will understand the difference between selling coffins and operating a taxi business to transport Christians to church. The latter, though permissible, is makrooh (i.e. not advised) because one is aiding non-Muslims in their acts of worship. Using the coffin is not a religious act of worship for Christians or other religions. Even people that don't subscribe to a religion, are buried in coffins. I, therefore, advise to avoid the second type of business.
And Allah Knows Best
Mufti Siraj Desai