The Founders Proposed a Religious Symbol For the First Seal of the US
On the very day that the American colonies declared their independence from Great Britain, July 4, 1776, three of the men who had been on committee that drafted the Declaration of Independence were charged by Congress with devising an official seal for the new United States of America. These men were Thomas Jefferson, Benjamin Franklin, and John Adams. While most of the Founders were church-going Christians, Jefferson and Franklin were among the more liberal in their religious beliefs, though both believed in a providential God, a Creator who endows men “with certain unalienable rights.”
Neither Jefferson nor Franklin were opposed to religious symbolism, as is evident by their proposal for a U.S. seal. Jefferson first recommended for the seal a scene of the “Children of Israel in the Wilderness, led by a Cloud by Day, and a Pillar of Fire by night,” from the Old Testament story in the Book of Exodus. Franklin drew from the same Biblical story and suggested this more detailed rendition:
“a pillar of fire in the cloud, expression of the divine presence & command, reaching to Moses who stands on the shore & extending his hand over the sea, causes it to overwhelm Pharaoh. Motto: Rebellion to tyrants is obedience to God.”
Jefferson deferred to Franklin’s description and together they submitted to Congress the seal you see below. Though it was not adopted their seal shows that two of the more theologically unorthodox Founders saw no violation of “separation of church and state” in proposing imagery from the Holy Bible in the official seal of the United States government.

... such symbolism was not adopted. It was likely realized this symbolism had less to do with the higher American value of "mutually guaranteed liberty for all" than it related to rather divisive religious beliefs. You wish to make that point that these men allegedly proposed these seals as some evidence they endorsed christianity and the christian bible as the official set of beliefs and practices of all americans and thus christian symbolism ought to be endorsed much the same way today.
It is clear they did not make such endorsement. Their focus was much more on the value of "liberty"
... where it belonged.