Within a short space of time, the numbers grew and people crossed the racial divides which to listen to him, and to participate in the questions and answers sessions which followed his lectures.
Although some Christians and Muslims criticized him for his blunt style, some people did convert to Islam because of his books and lectures, and da`wah (teaching Islam) soon began to dominate his life, with the audiences at his lectures reaching forty thousand. In 1957, Sheikh Deedat, together with two of his friends, founded the Islamic Propagation Center which printed a variety of books and offered classes to new Muslims. In 1986, he visited Saudi Arabia for a conference, and in his first television interview, became notable in the Arab world with his dynamic personality and knowledge of comparative religion. He then visited the United Kingdom, Morocco, Kenya, Sweden, Australia and Denmark on lecture and debating tours. Deedat's passionate, some say inflammatory, style of propogating the Islamic faith stirred confrontation not only with people of other faiths, but with nations as well -- Singapore banned him from entering their country2, France and Nigeria refused him entry out of concern that he would stir up "civil unrest" and Australia threatened to deport him.2 In the United States, he became famous for a debate with the American Reverend Jimmy Swaggart, witnessed by 8,000 people on the topic Is the Bible the Word of God.
On May 3, 1996, Sheikh Ahmed Deedat suffered a stroke which left him paralyzed from the neck down, and also meant that he could no longer speak or swallow. He was flown to a hospital in Riyadh, where he was taught to communicate through a series of eye-movements. He spent the last nine years of his life in a bed in his home in Verulam, South Africa, encouraging people to engage in da`wah. He continued to receive hundreds of letters of support from around the world. During these years, rumors spread throughout the Internet that he was already dead, and even some websites that contained his pamphlets mentioned as early as 2002 that he was dead.
On August 8, 2005, Ahmed Deedat finally succumbed to his prolonged illness and passed away at his home in Trevennen Road, Verulam in the province of KwaZulu Natal.
Many of Deedat's books were about comparisons between Islam and other religions, particularly Christianity. He wrote about topics such as the role of Jesus Christ in Islam and his belief that Muhammad was prophecised in the Bible, with many of the prophecies which Christians believe deal with Jesus actually deal with Muhammad. He delivered thousands of lectures all over the world, crossing all the continents and successfully engaging some of the biggest names in Christian evangelists in public debates, who believe that Jesus died on the cross and was resurrected, and whereas Muslims believe that Jesus escaped because of God's grace and God sent a substitute to die for him on the cross.
What makes Ahmed Deedat an interesting case is that he took comparative religion to a new level which involved heavy analysis of the Bible, rather then the traditional method of Dawah (preaching) that involved expounding on the Quran and Hadiths to a non-Muslim audience. Therefore his methodology was primarily to illustrate to Muslims and Christians that Quranic beliefs have fulfilment in the Biblical scriptures. The strength of his logic and argument tended to win him many debates, this was due mainly due to his reliance on Biblical verses that Christian missionaries have either overlooked or tended to ignore because it was at odds with Church doctrine. Hence in debates that involved disproving the divinity of Christ, the mentioning of Prophet Muhammed in both Old and New Testament, the corruption of the Bible, and most controversially, Crucifixion or Cruci-Fiction; Deedat was able to convince even the most skeptical of Christian audiences or at the very least, mute an effective counter response. Many former Christians (and even former non-practicing Muslims) worldwide attribute there conversion to Islam from having either watched a Deedat debate or having read his literature (although it would be an overstatement to attribute conversion to this alone).
This in turn had led to a rash of anti-Deedat sites, whilst some make legitimate claims of Deedats (at times) offensive and blunt style, they have had little success in countering the most popular of Deedat's arguments. This is mainly due to the fact that they have relied on sources external to the Bible which are subject to various interpretations, whilst Deedat has limited (as much as possible) his argument to the Bible (due to the fact that Christian missionaries traditionally ignore any external sources that contradicts the Bible in debates). Another problem of these sites is that they attempt to duplicate the Deedat template, e.g. criticism of the Quran, which on record has had rare success only because the nature of both books are different, eg while the Bible is filled with recorded history and events, the Quran claims to be a revealed preaching text, only using history when it is relevant to highlighting the moral of a story.
For better or worse, and despite the overt proselytizing angle he took, Deedat managed to bridge the gaps in the Christian and Islamic world, by the very least in giving Muslims an insight into the various nature of Christianity and how Islam could now be seen as a logical follow-up. Not to mention the fact that Christendom were able to at least better understand the differences and similarities that existed between Islam and Christianity due to Deedats's literature that was popularized in the past few decades (which for centuries, Western Christianity had viewed Islam as an alien monolithic rock), and thus Deedat was able to pioneer a new method in preaching that ironically had been traditionally the very tool of Western Christian missionaries.