If just one person does not believe in a religion and does a good deed, then it's the person that must get credit for the good deed, not the irreligion. Effectively making religion obsolete; well the good deed parts anyway.
That's why we test the fruits of the spirit, not the words of the mouth to find true Christ-followers.
How so, MMH? You have said that "Christians believe that Christ is savior", but that is "just a belief", it is just words of the mouth. To follow the example of Jesus is to yield spiritual fruit. But to attest that he is your savior is nothing but talk; by the way, he never ONCE suggested that he was your savior.