I was reading apologist Nabeel Qureshi's autobiography Seeking Allah, finding Jesus last week, when I checked Facebook and learned the terrible news that he has been diagnosed with advanced stomach cancer, with a 'grim' prognosis. He's asking Christians to pray and fast for his healing.

Nabeel is a former Muslim who is now an inspiring and effective evangelist. As he puts it:

As we pray for him, let's learn from him. His testimony has much to teach us. Here are a few nuggets I picked up from his book, which I'd say is essential reading for any Christian:

1. Conversion involves a huge change in culture, worldview and identity

Islam is the filter through which Nabeel understood the world, how he assessed truth, and he was "brimming with respect and pride for [Muhammed]". Doubt only came after multiple arguments that supported the reliability of the Bible and the rationality of Christian belief. This seemed to provide a foundation for being willing to question whether the Qur'an was trustworthy, and whether what he had been taught about Muhammed was true.

2.  Islam teaches its followers about Christianity in a way we don't teach about Islam

Nabeel had been told a lot about Christianity. Disbelief in Jesus' divinity and the Trinity is woven into Islamic doctrine. Nabeel believed that Jesus hadn't died on the cross and that the Bible had been changed (though he trusted other Bible verses that he'd been told supported Islam). When Christians spoke to him about his faith – which was rare – they didn't have the information needed to challenge these ideas, until he met David Wood and some senior apologists at university.

While he'd been taught to take a critical stance towards Christianity, he'd never seen this same stance applied to Islam.

3. There are more differences between Islam and Christianity than doctrine and belief

For example, Christians focus on the meaning of the Bible, but Muslims would see the words of the Qur'an as holy in and of themselves. Therefore reciting the Qur'an in Arabic is seen to be pious even if the person can't understand it. Also, Muslims don't expect to hear from God, other than in dreams. In the end, while Nabeel had extensively investigated the rational arguments for Christianity and Islam, and had accepted the former: it was three dreams and a vision that gave him certainty.

4. A Muslim's impressions of Christians may be negative

Muslims from the East have often been taught that Christians in the West are promiscuous – they wouldn't make the distinction that we generally make between the behaviour of practising Christians, cultural "Christians" and those who do not identify as Christians at all. He said that the first time he saw anyone reading the Bible in their free time was when he shared a room with David.

5. In the West, Muhammed is usually presented as a loving, peaceful figure

Nabeel was an Ahmadi Muslim, a sect that holds to non-violence. He heard that Muhammed only went to war in self-defence. When Nabeel investigated the historical hadith for himself he discovered this wasn't true. He was also shocked to discover the history of taking sex slaves following war – the kind of behaviour we're seeing from Isis today.

"The peaceful practice of Islam hinges on later, often Western, interpretations of Muhammed's teachings, whereas the more violent variations of Islam are deeply rooted in orthodoxy and history," says Nabeel in Seeking Allah.

6. Differences in culture go beyond religion

Western cultures assess truth primarily through reason and critical thinking, but Nabeel says "people from Eastern Islamic cultures generally assess truth through lines of authority, not individual reasoning". Elders and leaders are assumed to have done the thinking, they know best and they should be obeyed. The honour/shame sense of morality is also very different.

7. Living between two cultures is difficult

As a child of immigrants to the US, Nabeel was shaped to some extent by Western culture so he became different from his parents, but he felt he was "too Pakistani" to fit in well with his US friends.

8. The surpassing worth of knowing Christ

Though Nabeel was a devout Muslim and saw great beauty in Islam, it was nothing compared to knowing Jesus. "My heart was filled with a new joy, the joy of meeting God Himself," he said. "I thought I had known Him my entire life, but now that I knew who He really was, there was no comparison. Nothing compares to the one true God."

9. For a Muslim to accept Jesus requires sacrifices that Western Christians can't even imagine

Nabeel had a loving upbringing in a very close family. He knew that accepting Jesus would devastate this, and that he could be cut off forever from his parents. He had to weigh this up when he gave his life to Christ, though he was guided with Bible verses such as "Anyone who loves his father or mother more than me is not worthy of me."

His father said, after being told of his son's conversion: "I feel as if my backbone has been ripped out from inside me."

10. Why does God wants us to tell others, even if it hurts them?

Nabeel was filled with despair at the pain he'd caused his parents. What comforted him was words from God: "This is not about you". He was shown that the whole world is in desperate need of the message of Jesus Christ, and that they need to be told. Ultimately it seemed, God judged this as more important.

Are we considering this message, and the desperate need of the world to hear it, as the most important part of our lives? What are the barriers that stop us from doing so? If God requires Muslims to make such huge sacrifices, and even risk death – surely He requires those of us with much less to lose, to give even more for the sake of the gospel.

Heather Tomlinson is a freelance journalist who communicates the Christian faith. Find her at www.heathert.com and @HeatherTomli