But there are a few examples around the world of the magic that can happen when both come together.
One of these is the Mezquita in Spain's Cordoba.
|Inside the Mezquita|
Today, the Mezquita is officially the Cathedral of Cordoba, but it's strong Islamic architecture tells the story of how it was once a mosque.
In Cordoba, the result is the Mezquita.
My friend and I have plenty of opportunity to admire it, as by luck our hotel room overlooks the main gate. Here locals and tourists dodge horse-drawn buggies and gypsies trying to sell sprigs of rosemary (I'm still recovering from receiving the "evil eye").
From the outside, the Mezquita holds its secrets close. It's surrounded by an imposing stone wall, interrupted by ornate gates, that offers little hint as to what's inside.
|The forest of arches|
Almost as far as the eye can see is a "forest" of arches that make up the Mezquita's expansive hall.
But the Mezquita has one more surprise for us. Like entering a clearance in a forest, we stumble into the ornate and light-filled Catholic cathedral that sits in the middle of the building.
|The Catholic cathedral at the heart of the Mezquita|
It's as though someone literally just plonked a cathedral down in the middle of the mosque (which is roughly what happened when the region's Islamic rulers were overthrown by Christians).
|Looking back out to the forest of arches|
|The Christian's ornate cathedral|