If you think that we are a secular Republic, you will no doubt be astounded to learn that Jesus is mentioned in the US Constitution and that the President is explicitly exempted from working on the Sabbath. And lest you think this is some how a mistake, the Articles of Confederation, also mention God and Jesus prominently in the document. The Declaration of Independence, which is the document which actually founded the nation, also bases it's claim to independence from rights given by God.
Also Abraham Lincoln would disagree with you. He thinks we are a Christian nation.
No, we have been lied to and deliberately misinformed about this. We were NOT founded as a Secular Nation. We were founded as one that recognized different of the 13 states had different official state religions which were all denominations of Christianity, but denominations with different doctrines, and concerned about how they would be treated if one denomination was chosen as the official religion.
The exclusions of religious tests to hold office were done to allay they fears of differing states with different dominant denominations, not to create a "secular" government.
But we have long been lied to and mislead about this.
You’re cracked. The Constitution makes no mention of Jesus or God. The Declaration of Independence cites a “Creator” (not necessarily the Christian God, and indeed Jefferson, who privately denied Jesus’ divinity, was possibly a deist, but definitely not a Christian). However, the Declaration, unlike the Constitution, is not a part of US law. It’s purely an inspirational document.