Without experience we would know nothing, true. Yet all experiences are subjective, and are susceptible to inaccurate self interpretation.
A God experience would have to be irrefutably true, and that takes reasoning about the experience. There would be no room for doubt. No experience is infallibly 100 percent absolutely clear as to its accurate and complete truth. Perhaps a certain percent of personal experience is as is, but the interpretations of experience always can be questioned and it would be rare indeed to get an infallibly true self interpreted personal experience; where you know that you know that you know that what you are experiencing is God.
I would never claim that a subjective truth is infallible. Quite the contrary, subjective truths in general are very fragile as they tend to run afoul of practical reality. If I were to believe that I no longer needed to eat so long as I drank out of a specific "holy" cup then I would soon discover the protest of my stomach and body if I didn't come to believe otherwise.
There are more subtle subjective experiences which are deeply formative of one's own sense of meaning...they way a parent treats a child, how a first love interest relationship works out, whether one wins a fist fight with a bully, etc...these things expose us to our sense of ourselves as subject to the consequences of our reality and experience on a deeply personal level and address such questions as:
- Am I respected/respectable?
- Can I have success?
- Am I loved/lovable?
In general terms these are value questions which we rationally determine based on our experience of life. We realize that our actions, our character, our value is a matter of rational assessment and we are frequently comparing ourselves to others or being comparable to others in an effort to determine that level of value. The ability to objectively and fairly assess our personal worth against those of others, to have faith where we are found wanting (and remember as a child just how much that assessment is dependent on the determination of one's parents and later peers) to handle well when we are gifted...all these things are not answerable to science as much as they are answerable to the input of others in one's environment and one's own self-determination. To find one's value amidst a throng of objectively like others (in the context of a more or less democratic society) is to try and understand why "I" should have when others don't or why "I" should go without while others don't.
William James the American psychologist studied and classified types of religious experience and found that in varied cultures and contexts there were common identifiable patterns of experience that people claimed they had and those experiences shared qualities objective in nature. Even as those experiences created a sense of value in those who had them (and sometimes they didn't), they often were not experiences those individuals chose and as such they were experiences that happened to them. How they interpreted those experiences often would have to do with the community that would and could interpret those experiences or provide a language and frame for doing so.
It is possible to have an intense personal dream or vision which so deeply impacts one's sense of meaning and estimation of the value of creation that one cannot sincerely dismiss that experience as a subjective hallucination. To do so would so corrupt an appreciation for the world, a tolerance of its evils and a sense of value in one's self as to be almost suicidal to one's integrity. This is not to say that such experiences are an excuse to devalue others who have not had these experiences, to devalue science and other forms of objective knowledge or to abandon one's sense of responsibility to others because one is personally "saved". In fact most religions teach against this very thing although, with deep irony, we see so many act otherwise.
Self-interpretation, in the end, happens in a group (family, peers) or community (cultural, religious) which fosters a certain set of mirrors or metaphors for how one sees one's self. That mirror is itself subject to an individual's evaluation and very often not based on factors that are entirely relevant. To the extent this is true we all face the prospect of recognizing cracks in the glass and obscuring soil on its surface. Sometimes the mirror is, through the course of a rational evaluation of experience, largely abandoned. And sometimes one is handed a polished surface so neatly suited to an individual that it persists because of its uniqueness and value to that individual. They can go to work, solving peer-reviewed problems in science by day, and read fantastic tales from their spiritual books by night and never be troubled that the two don't literally correspond.
If you have ever walked out of a theater with a renewed sense of yourself, your potential and that of your society, then you have had a religious experience...one that provides you a sense of appreciation for the world you find yourself in, an understanding of how you should act in that society, and an understanding of what you may become in your future. The surviving religions may need to undergo some serious changes to maintain their role as a healthy contributor to modern life, some more than others. But in terms of coming to a deep appreciation of one's self in spite of all the suffering that one can and is often subject to, there is no better science than religion.