On Religious Superiority?

A thought experiment for your consideration:-

Two people (1 and 2) undergo moral development over the exactly the same period of their lives and at exactly the same rate. They form identical principles, philosophies and belief systems and, for the sake of argument, each lives their life altruistically, selflessly, and exactly as the other would in the same situation.

The only difference is that person 1 bases the way they live their life on the principle text of religion A and person 2 on the principle text of religion B. Each text asserts that it is the only true text and that only followers of that text are righteous and will be rewarded for their lives. Each text encourages proselytisation.

Suppose a person 3 comes along, a fervent follower of religion A. Person 3 is told only the information of the first paragraph. Will this person be able to decide which of persons 1 & 2 will be rewarded for their lives? Will person 3 be able to decide which of 1 & 2 should attempt to persuade the other to convert?

Of course not!

What if person 3 is then told the content of the second paragraph? Now person 3 knows which religions each of persons 1 & 2 follow. Why should this make the difference?

My personal beliefs are that nothing can justify this difference. Food for thought...

Is my experiment a vast oversimplification? Yes. Obviously no two people share identical principles, philosophies and belief systems. However, few people can argue against altruism and selflessness being fundamentals of leading a good life, regardless of their religious beliefs or lack thereof (and I am deliberately ignoring objectivism). Regardless of whether anything happens after life, surely adhering to these fundamentals is something we should agree on as being more important than the route one takes to get to them...