From a Royal Mail postman to an Islamic State (Isis) militant — Harry Sarfo's journey helped him understand the reality behind the terrorist organisation's religious propaganda. Today, sitting in a prison cell in Germany, the former jihadist is eager to warn others not to get influenced by the IS's (Daesh) version of Islam.

In an interview with The Independent via his lawyer, German-born Sarfo stressed that "This is not the path to paradise; it is the path to hell", a lesson he learned when he joined the group in April 2015.

At the time, the former postman was influenced by videos showing IS recruits helping Syrians who were suffering under Bashar al-Assad's regime. But after switching his mail bag for a rifle, the reality of the situation soon became clear. "When they speak in their videos with weapons, it feels like they're calling you. But in reality it is all a lie. Once there, you'll realise but it is too late to turn back. They know you can't leave," he described.

Sarfo trained as a special forces fighter and even appeared in a propaganda video before deciding he did not want to be part of an organisation that regularly conducted stonings, beheadings and attacks on innocent civilians.

"I came to the conclusion that this is not the path to paradise, it is the path to hell," he said. "I knew that if I died there I would never be able to enter the gates of paradise. Instead of freeing the Syrian people and uplift them, they've created another regime."

Sending a warning to Muslims who may be considering joining the terror group, Sarfo said, "Learn your religion and you will find out that most of the things these people are doing are in-Islamic."

A few months after joining IS, he escaped from the stronghold of Raqqa and made his way back to Germany where he was arrested in July. He is now awaiting trial on terror charges.