First of all, they are ahistorical. They do not describe the actual historical process of our formation. You would think that a "sources" statement would describe an intellectual history. There is a when and a where and a who behind each of these sources, which is not explained.
For example, our historical origin is in Protestant Christianity. Indeed, many of our churches were actual Protestant Christian churches for long periods of their history. It is also true that for many current Unitarian Universalists, their personal religious history begins in Christianity. Unitarian Universalism sprouted from a specific branch on the Christian family tree and our sources statement should be able to explain that.
One of our most important sources is the humanist movement of the 20th Century. The Sources statement bows to it in the Source Five. But the Sources statement does not describe the revolutionary character of Humanism as a religious movement. Historically, humanism makes no sense except as a rebellion against liberal Christianity. Our Sources do not convey that fact that our religious movement is rooted in both sides of what seemed to be a "zero-sum" theological conflict.
I believe that the Sources statement is a like a family narrative that hides, or disguises, or minimizes, a family trauma. The falsity at the core of the narrative is the implication that to our ancestors at the time whether or not one believed in God was a mere difference of opinion without any lasting consequence. This is like thinking that Cain and Abel had an minor difference of opinion on agricultural policy.
If the humanist rebellion against Protestantism was the trauma, liberal religion survived it. But how? Because how we survived the trauma has formed us, even more than the trauma itself. Theologically, the mechanism of survival was to move to a stance of agnostic pluralism. Agnostic pluralism says that no one can really know the ultimate truth, so therefore many opinions about the truth can coexist.
The move to agnostic pluralism is the hidden, or buried, event that dictates the form of the Sources statement.
Each of the other statements refer to a historic event in our common intellectual history. Those events are presented as disconnected summary ideas abstractly stated. Hidden in those summary abstractions are the influence of the Christian social gospel, the Civil Rights Movement and the subsequent liberation movements, the rise of Western Buddhism, global immigration, the women's movement and on and on. All of this social history has been our sources, and all of it is hidden when we talk about those Sources.
None of this rich intellectual history is revealed in the Sources statement. The statement is designed to blur this history in order to avoid conflict.
The Sources are, therefore, not only ahistorical; they are idealist. Movements of people and of the Spirit, are reduced to summarizing phrases and then those disembodied ideas are thrown into a pot together without explaining their interrelationship.
The result is that our sourcing statements promote a theological pluralism that is individualistic. We have a cafeteria-style history, a salad bar of memory. You pick and choose. The Source statements frequently refer to "we", to "us" and to "our". But in all cases, that collective pronoun is assumed to partial and voluntary.
Note how we assume that the Principles make a unified whole, but the Sources do not. And so, the Principles take on a normative dimension -- they describe how we should act, a set of guidelines to which we can held accountable. The Sources defeat any attempt to appeal to a common history, or to common obligations that arise from our past.