Hindina Janumada Papa Karmagalu

I have heard this famous and a popular statement, "Hindina Janumada Karma/papa" from almost all of my hindu friends and from my relatives (me being a Hindu).
To bring you to the context of what I am speaking, I have heard this from people whenever they are questioned or asked about the pain and the suffering that one undergoes in terms of well being (health or wealth or relationships) that its all because of one's previous birth's sin - "Hindina Janumada Karma" - translation - "Previous Birth's Actions".

Who has set this rule, If God has set this, how did people here get to know? did he pass them through some means, wait, you might think its written in Vedas, Purana, all the sacred scripts, but then is there any proof that God himself wrote this? no... it could just be the pure assumption of the great authors... well they were also human beings, common men who sore up to that level, who were wise and matured but still, I don't believe that they could make up such statements which are slightly illogical, but I do agree with all other rational thoughts and commentaries they have made, very highly appreciable, well probably I don't even have the right to comment on them on their work. But this very statement and the concept behind is slightly so very irrational and not an appealing reason to convince me.

I reckon that the person who interpreted the pains and sorrows one undergoes in this birth is due to the previous birth's action (bad deeds) are may be, to imbibe the fear of what could happen to the one in the next birth if he did the wrong deed in the present…. so in that fear at least let an individual try always to be good and do good. This philosophy "Hindina Janumada papa" is just a medium through which people can become more refined (with the fear in the background)…

Okie, I agree, if the person is not matured intellectually he would need a preaching like this to make him a good human, let me give an analogy, it is similar to teaching a kid that he should behave well, should not harm animals/steal something - else the result would be that God would punish him.

But as we grow stronger in the maturity ladder, should we not know or understand that, we should be good because our conscience knows the difference between Good and Bad, Good brings happiness to all, Bad would cause pain and chaos… its simple.
Now the idea of "Hindina Janumada Papa", will it not indirectly imbibe the negative qualities like "Selfishness" in a person - How? - here it is.. So if this is your perception, then you would be good just to make sure you are benefited in your next birth, forgetting about humanity, you do not bother if a person is hurt or not, all you bother is about your credits on the good scale which you want to carry forward to your next birth…. is this not being selfish?

Well, my take is, when I can clearly differentiate between good and bad, why should I be doing bad or something which harms others. Its better not to think what benefits us or how much profitable we become when we do good/bad, just leave the ego, stop being greedy and selfish and think, what harm are you causing others, it is definitely not a good thing to see someone unhappy until and unless you are a sadist.

I remember my mom saying, "when you tend to do something, there is an inner voice which says, this is bad and you should not be doing it, also gives a hint of the probable aftermath of these actions, if you really adhere to that voice then you emerge as a true winner".

It is good to have a clear conscience, it is better to obey it and the best is to, stop being selfish!