"Close your eyes and try three times," our young guide explains. The pressure's on. Throw the pebble in the right-hand hole, I get heaven – the left and it's eternal damnation.
After two tries I'm somewhere in purgatory; on the third, thankfully, I'm saved.
The conical temple at Lalish, in Iraq's Kurdish mountains, is the holiest site in the Yazidi religion, a secretive sect influenced by Zoroastrianism and Sufi Islam. It is here they believe the universe began.
The Yazidis, whose numbers have dwindled to just some 500,000 and are largely concentrated in Iraq, have suffered widespread persecution throughout history.
They worship Tawuse Melek, a peacock angel, the most powerful of seven archangels which they believe God has tasked to rule the Earth. The Yazidi belief that Tawuse Malek refused to bow down to other beings, paralleling the story of Satan in the Muslim and Christian faiths, has led to them being branded as devil worshippers.
Our guide shrugs off the accusation and laughs off our other questions about the religion's more bemusing practises such as refraining from eating lettuce. One legend has it that a massacre of Yazidis took place in a lettuce field, leading to a vow never to eat lettuce again.
Unfortunately for the Yazidis, the attitude of our taxi driver in the nearby city of Dohuk remains an all too common one. "Muslims, they have Mohammed, Christians, they have Jesus, Yezidis, they have Satan," he laughs.