High school students around the country used to take a course that introduced them to many of the world’s religions. In classes filled with children of many beliefs, teachers would talk about how a particular faith developed and how it spread.

Today, when it seems that the faithful in one religion are inevitably taking potshots at believers in another religion, people may have forgotten how life was in past eras. People of different faiths used to live and work side by side with little concern. At one time, Jews served as advisors and heads of state in Muslim countries. Christians and Jews worked together in Catholic Spain. Christians lived in harmony with Muslims in the Middle East.

Once, Jewish and Christian icons could be found in the Ka'baa, the holiest religious object in Islam, located in Mecca, the holiest city in Islam. Even today, Jerusalem hosts the Dome on the Rock, a sacred Islamic mosque, side by side with the Wailing Wall, the last surviving piece of the great Jewish Temple that once existed there.

Visitors to Jerusalem, the capital of Israel, can see religious Jews, wrapped in prayer shawls, trudging along ancient streets along with Muslims and Christians. Overhead, the cry of the Islamic muezzin, calling the faithful to prayer, rings out along with the tolling bells of Christian churches. The flag of Israel with the Star of David in its center flutters in the same breeze.

Such situations are too rare. Members of the three religions seem to fight more than they pray together. Over time, the three great religions have become separated by seemingly unbridgeable chasms. Actually, they are very much alike.

• They share a common heritage. They each tie their history to a single event and a single person who lived maybe 4,000 years ago.

• They worship the same God.

• They have similar holidays. Easter, for example, the holiest day in the Christian calendar, is tied directly to Passover, the most significant holiday in Judaism.

• They each believe Jerusalem is a sacred city.

There are many more links between the three faiths than differences.

The passing years have clouded how much Judaism, Christianity and Islam have in common. In fact, those comparative religion classes aren’t offered any more in public schools. Too many people today have no idea how much these religions share.

Maybe it’s time to review the past as a way to create a peaceful path into the future.