Victor, can you please describe a little more concretely what you mean by 'personal testimony' in a non-religious sense? What would be your alternative? What is your ideal world or your ideal forum?
It seems to me that we must encounter the world through our own experiences first and foremost. As we mature, we learn to take the experiences of others into account, but even that is indirect, filtered through our understanding of those people's experiences. There is no such thing as being purely objective, because we are always limited by what we have experienced, biased by what we can perceive. I remember the day I realized that other people had consciousness too, and it blew my mind... I wanted so badly to experience their consciousness, to see the world or a situation how they saw it, but eventually I realized that the best I could do was imagine it based on my own understanding of myself and of them as individuals.
Do you disagree that a person's experiences are vital in shaping how they have developed into the person which they are? How can we improve, how can we learn to see things from others' perspectives if we do not understand our own perspective?
I agree that too much self-inspection can actually be blinding though, both to insight into ourselves and to insight into other people.