Open source religions attempt to employ open source methodologies in the creation of religious belief systems. As such, their systems of beliefs are created through a continuous process of refinement and dialogue among the believers themselves.
Among the first examples of this movement, Yoans (followers of a religion called Yoism) claim that their version of open source religion does not have allegiance to any spiritual guide, rather the sense of authority emerges from the group via consensus.
It seems to me that the issue here revolves notion the idea that "truth" is something that "emerges from the group via consensus." This runs contrary even to our observation of the physical world around us (which Yoans would claim as the basis for truth). The laws upon which the physical world operates are independent of our "consensus" concerning them. The whole scientific establishment is founded on the belief that things like gravity are not dependent on individual (or group) opinions.
To remove the independent source of truth is to remove it's meaning. If truth is something I or we can create ourselves, then it is arbitrary and useless as a guide or standard for behavior. Only the truth I must "discover" not "create" has value. If I must discover truth then it must have been created by something outside of me and more than me.
I come back to what I said earlier, God=Truth. If God is not the source of truth, then I feel no inclination to attempt to abide by truth's dictates.
For more on the topic, check out relativism on C.A.R.M.