People validate their own reilgious experiences in a variety of differant ways. For example, many in the power of prayer and see all of their life events as tied directly to the will of God. Others believe that they have been witnessed or experienced miracles of healing and revelation.
Jehovah's Witnesses are unique in that they typically ignore traditional means of verification, seeing them as superstitious, overly emotional, and self absorbed. Despite this, JWs still go about process of validation. I think it just happens to be more subtle (and possibly a bit more intersting).
As a person converts to the JW faith they begin to adpot a unique worldview. "Gods people" are on the move, preaching that the end is near. All of the worlds religions are corrupt and evil. The worlds political systems also are corrupt, and the United Nations is about to destroy religion as we know it. Essentially, there is one giant world conspiracy against Gods people and the truth which has manifested itself in many differant ways. As a person converts, they begin to see the world in these terms. Worlds events validate their belief that "the end is near" and that humanity will soon be subject to Gods wrath.
As a Witness I began to draw on these things not only as proof that the JW experience was valid, but also used it to validate my belief in God. I wasn't seeking to experience God through prayer or mystical experience, instead I experienced him by living through the JW worldview.
This especially extended to the organization. I eventually came to believe (as I feel many JWs do) that it is basically Gods responsibility to provide us with an organzation. Think about all those times the Watchtower told us how loving it was for God to give us his organization. I think many JWs eventually come to believe in the opposite of that statement. If such an organization was not in exsistance God would not have been doing his job. It's easy to see how many JWs get the feeling that if there was no organization God would be cruel and unloving.
What's interesting about this IMO is that JWs will give more wieght to these things than other issues. Usually the evidence given to support the validity of the Bible and the exsistance of Jehovah are rather bland and lack depth. However, information that builds up the miraculous nature of the organization is overflowing (think Revelation book vs. "Is there a creator who cares" book). So it seems to me that the way in which a Witnesses experiences and validates his belief in God (not just his faith in the organization) is more directly tied to the organizatinal experience.
Just kind of ranting a bit...