CoolFire brought up an interesting topic about the "irrelevance" of some spiritual teachers. I actually do have sentiments along the same lines. My feelings are not identical but they do converge with his idea at some point and then diverge again.
I have had interest in Buddhism since my teenage years yet now I feel distant from it. By interest, I mean I used to read some books related to Buddhism or go to forums about once a fortnight.
However, I feel that basically religion tries to explain most things based on false(on hindsight) information. To make it short, I will say that the conclusions it reaches are true for the information that it possesses at that time. However, most of it is wrong as time passes and new information is divulged.
Buddhism can be summed up in a limited way by Newton's third law of motion "Every action has an equal and opposite reaction". What did you think Karma was? It is basically the equal and opposite reaction to your actions. By opposite, I don't mean the negative reaction but something which affects you instead of you affecting something else.
At that time when Buddha conceived this, it was probably extremely profound. But now when you read about it, it is still profound but science has quantified this revelation and has taken this understanding deeper and at a more profound level. For example, the way I think about it is that a person's thoughts change the physical brain cell pattern and affect him later on. It's cyclical. Buddhism takes this single concept and extrapolates it to different ends.
I am not a Buddhism expert and I am sure there are a lot of other "concepts" in Buddhism.
This is a simple example and something that science can actually test. So am I saying science has reached a point where it can explain almost everything?
No. But I do think the unexplainable will be explained; of course, other unexplainables will be discovered. But surely, it will boil down to a single unexplainable some day. Maybe eons.