I am not at all religious, so I may have a little trouble with what I am trying to say here, so please bear with me. Someone with a lot more knowledge than me is more than welcome to quote the exact words, but here is my (extremely) basic recollection of how it goes.
There is a quote somewhere in the bible that tells of a father (I think) that gives his three? sons a sum of money. They go out and one of them holds onto it, does nothing at all, but does not lose it. Another saves it and multiplies it slightly and the third goes and invests it, multiplying it greatly.
The father comes back and asks what they have done with the funds. He is unhappy with the first because he has held onto the money so tightly, worshipping it in fact, affraid to use it. The second, he says was also unworthy due to the fact that the money had not grown enough, and the third he is very happy with, showing that not only has he been a good steward of this money, but has made it work for him and grow substantially.
My (very) basic understanding is that you are unholy to NOT put your money to use. As a Christian you should strive to be able to invest to support yourself.
Let's take your Christian friend who does missionary work as an example. Imagine what good they could do if they had an income stream (maybe from their row of shops) that is passive. They could fund themselves to go wherever they want in the world to do whatever good works is their will.
