The Ultimate Sin
It seems to me that people swing from one extreme to the other, you will go straight to hell if you even think about eating a fish, and on the other side, you keep every single fish you catch. I think that just like virtually everything else in life moderation is the best policy.
Besides my father, the largest influence in my life when it came to fishing, and the outdoors in general, were my grandfathers. Both my maternal and paternal grandparents grew up in the depression era rural appalachians. The pic below is of my grandfather and his brothers in a rural logging camp where my great grandfather worked. I frequently fish the stream that is right beside where that camp was.
I am happy to say that the times are changing. Through a combination of education and new regulations those same streams that did not have any fish are now full of native fish. Even the southern appalachian brook trout that were pushed to the brink of extinction in a lot of areas are making a comeback.
Today in my home state of North Carolina there are many "Delayed Harvest" streams, delayed harvest means no fish may be possessed between October and June, during this time you can still fish but all fish must be released and no bait may be used, only single hook artificials. During this time is when the state stocks these streams. This regulation protects these stocked trout allowing them time to distribute through the stream and also protects the spawning times for both brown and rainbow trout, fall and spring.
I also mentioned education. Fishing clubs and organizations such as Trout Unlimited have done a great job of championing catch and release fishing, sometimes taking it too far, but a great job nonetheless.
My personal philosophy, is that as long as you stay within the limits of the law and don't take more than you need, go for it! Fish are a renewable resource and a dang fine meal after a hard day catching them.