I used to do a lot of talk radio, which means I often appeared on conservative shows. Every now and then, someone would call in with what they thought was a killer argument against separation of church and state: My public school, town or state can do what it wants when it comes to religion because the First Amendment applies only to Congress. So there!

Nice try. That argument might have flown 200 years ago, but these days it’s a dud. It fails because of the official ratification of the 14th Amendment, which occurred on July 28, 1868 – 150 years ago on Saturday. (Some sources list July 9 as the ratification of the amendment. That is indeed the day the last state needed to make it part of the Constitution passed the amendment, but the secretary of state did not officially certify this until July 28.)

It’s certainly true that the First Amendment and indeed the entire Bill of Rights originally applied only to the federal government. James Madison, the father of the Constitution, argued for extending those provisions to the states as well, but the political support was not there.

So, while the federal government was barred from making any laws respecting an establishment of religion or prohibiting the free exercise thereof, states were not. Some chose to retain officially establishes churches. The last state to give up its official church was Massachusetts in 1833.

That changed when the 14th Amendment became part of our Constitution. One of a series of post-Civil War alterations to the Constitution, the 14th Amendment, among other things, makes it clear that states may not violate the fundamental rights of the people.

The relevant section reads, “No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.”

The Supreme Court in the latter half of the 19th century was often conservative and for a number of years resisted the intent of the amendment. That began to change by the early 20th century. In 1925, the Supreme Court ruled that states could not infringe on freedom of speech. Fifteen years later, in a religious freedom case called Cantwell v. Connecticut, the high court ruled definitively that the church-state provisions of the First Amendment apply to the states as well.

The effect of the Cantwell ruling was dramatic. Previously, the states had largely been able to decide how much church-state separation to allow within their borders, but now the Constitution required separation nationwide. For example, parents began challenging coercive forms of prayer and Bible reading in public schools as early as 1868 under state constitutions and laws. Some states invalidated the practices, while others upheld them. The rights of children were at the mercy of geography. That ended in 1962 and ’63 when legal challenges to coercive forms of religion in public schools were brought under the U.S. Constitution. The U.S. Supreme Court struck down such practices in two landmark cases – Engel v. Vitale and School District of Abington Township, Pennsylvania v. Schempp.

In short, a proper enforcement of separation of church and state would be impossible without the 14th Amendment.

When we think of the First Amendment, James Madison comes to mind. The 14th Amendment had a champion as well. His name was U.S. Rep. John Bingham (R-Ohio), and he was the primary author of the amendment.

Few remember Bingham today, and that’s a shame. This anniversary is a good time to reflect upon the legacy of freedom he gave us.