Is there One God or Three? How does one reconcile the "One God" of the Sh'ma with the "Three Persons" of the Trinity?

The doctrine of the trinity has been at the heart of much theological controversy. The routine objection is that the doctrine sacrifices monotheism to "tritheism." But this objection thrives on a misconception of divine personality in the image of disparate, individual, human selves.

This type of rationalistic apologetics, promotive of trinitarianism on speculative rather than revelational grounds, regrettably encourages this misunderstanding.

How does one reconcile the "One God" of the Old Testament with the three "Persons" of the New Testament Trinity? The Sh'ma of Deuteronomy 6:4-5 clearly emphasizes the singularity of God, which is also reconfirmed in the ten commandments (Exodus 20:3), etc.