Many of the same men responsible for, and who ratified, the Constitution, specifically the first amendment:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.
were also responsible for other State Constitutions; they also — as government officials — prayed sectarian Christian prayers in public schools and at government meetings and public events. They taught from the Bible in public schools and used government buildings as churches. This was the case for their generation and many that followed.
Now we are told that such expressions of religious faith by government officials and school officials are unconstitutional. But it doesn’t seem that the men who crafted the Constitution thought what they were doing was unconstitutional when they did the very same things.
I have to ask of someone arguing that doing what the Founders did when they mingled religion and government is unconstitutional. Is it reasonable to believe the Founders didn’t understand the document they crafted? Or is it more reasonable to think maybe you are misunderstanding the Constitution?