Arthur, I've also heard the Trinity described as the Father, the Son and the Holy Ghost.
It's immaterial. The point is that they had an explicit opportunity to insert Christianity into the Declaration, and they did not. Jefferson, a Deist by his own claim, writes about this incident quite a bit. One of the three things he aked to be remembered for was his "Statute on Religious Freedom" in Virginia. It codified freedom of religion for everybody, including those who held no religious views.
There is no doubt that Christians had a positive influence on the founding of our country. But I'll repeat, our strength comes from freedom and respect for individual rights. The founders could have held Christian principles and expressed them in a monarchy. They didn't. They were trying to create the best government they knew how, not trying to express their religious points of view.
... which are Christian values!
Jefferson was a Unitarian. He had no problem with state taxes being raised to fund the Unitarian church.