Why can't we withstand the sectarian currents any more?

The differences and hatred I see in people that I meet remind me of the days when such things were rare

'One hand does not clap," says an old proverb.

The other day I remembered the person who used to say this to us regularly in class when we were children, and I realised how much the world has changed.

An Egyptian, she was a respected teacher of fiqh, or Islamic jurisprudence, who taught one of the Islamic classes at an all-girls school in Jeddah. While curricula have been revised in recent times to make them more moderate, schools in Saudi Arabia have several classes dedicated to different aspects of Islam, as well as the Quran. When I was a student, there was no room for debate or discussion; the teacher would give a lesson and our role was to memorise it.

While a fiqh class ought to be about Islamic laws, it often ended up in a lecture on the "enemies" of Islam, such as the "Kafir" - the infidel or unbeliever - and how we as Sunni Muslims have to unite against anyone who stood against us. There were times when she would refer to Shiites as the "others", without explaining who and what they were, and why we should not trust them. To be honest, I had no idea what a Shiite was until I was an adult and I ended up as a journalist in Iraq. It was in 2003 and the sectarian rhetoric was starting to divide neighbours and families.

Coming from a mixed cultural and religious background, I was brought up to respect everyone. As long as someone was kind-hearted, it didn't matter what that person's background was.

Sectarian talk was banned in our house and I feel it should be banned in all homes.

But then again, some form of "us" versus "them" always creeps in. When I was a child, some people would jokingly call me a communist, because I was born in Poland when it was under the control of the Soviet Union. Once I was given a red hat from a Saudi friend, who called me "comrade".

While it was taken lightly in my society - some even considered it fashionable to be communist - communism was frowned upon in the Middle East and feared in the West.

As for us, the students in that class, we were all united: we were class A, and in our minds we were "the best" in school.

Within our class, there was an athletic group (of which I was a member because I played basketball and volleyball), a nerdy group, a pretty group, an environmentalist group and so on. We were all Muslims but with different nationalities. Some had Christian mothers but that didn't matter much. Perhaps you would be asked a couple of times if your mother had converted, and that was it.

I forgot about this teacher and others who were very strict in their interpretation of Islam until I revisited my school a couple of years ago. There I found out that she was a member of the Muslim Brotherhood in Egypt, and that she and her family, including her husband, who was also a teacher of Islamic studies in the boys section, were asked to leave Saudi.

I also found out that I actually had two Shiite classmates who always remained quiet out of fear of being picked on by the rest of us.

I reconnected with one of them and she told me how difficult it was to be part of the class during certain teachers' seminars. She also told me that while we didn't know about her religion some of the parents of the other students knew, but it didn't make any difference.

Why are we so divided now, so much so that your sect is the second question after your name on official documents and in social gatherings?

The differences and hatred I see in people that I meet remind me of the days when such things didn't matter. Today it is all about what makes us "different" from each other. Friends who always used to hang out together now can't do so without arguing and debating about politics and groups.

We simply can't just sit and agree anymore – one of us has to be right, and the other wrong.

On Twitter @arabianmau