1. Thomas Jefferson explained why being "one Nation under God" is important.
Thomas Jefferson and our other Founding Fathers understood that the government does not give us our freedom. Our freedom comes from God, and the government was established to protect that God-given freedom. That was their justification for the American Revolution as stated in the Declaration of Independence. Jefferson wrote:
"We hold these t***hs to be self-evident: that all men are created equal; that they are endowed by their Creator with certain unalienable rights; that among these are life, liberty, and the pursuit of happiness; that to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed; that whenever any form of government becomes destructive of these ends, it is the right of the people to alter or to abolish it, and to institute new government laying its foundation on such principles…"
No king or emperor, no president or congress, no court or crowd gives us our rights. They come from God himself and are unalienable. And the Founders built America's "foundation on such principles."
2. Abraham Lincoln explained why being "one Nation under God" is important.
Abraham Lincoln understood that the nation's unity and freedom depended upon being one nation under God. In the Gettysburg Address, Lincoln used the exact phrase, "nation, under God," echoed in the Pledge of Allegiance. He began his address by referring to the Founding Fathers' foundation in God-given rights:
3. Martin Luther King, Jr., understood the importance of being a nation under God.
In his "I have a dream" speech, Martin Luther King, Jr., explained that:
“When the architects of our republic wrote the magnificent words of the Constitution and the Declaration of Independence, they were signing a promissory note to which every American was to fall heir…I have a dream that one day this nation will rise up and live out the true meaning of its creed: ‘We hold these t***hs to be self-evident: that all men are created equal.’”
https://gogateways.org/articles/2018/1/31/why-under-god-must-remain-in-the-pledge-of-allegiance