A few weeks back I was about to witness to a man standing outside of a shopping mall smoking (the man, not me) when a young Muslim heard me mention Jesus Christ and stopped.
I knew he was looking for a debate, but since I have learned better than that, I decided to engage him;-) If you think you will win souls bound in Islam by debates alone then you are very wrong. We need God to be involved. I entertained a distraction to witnessing to someone else because I genuinely felt that God was involved with this new encounter.
To cut a long story short, everytime I countered his false ideas, fed to him by some demonised Muslim teacher who is perpetuating false-hoods regarding Christianity, he responded that that was simply my opinion and what he held to was true. I of course said that I was bringing truth to him, not offering an alternate opinion to be accepted or rejected, but throwing life-lines of hope to someone bogged down in a mire of false religion.
Probably the strongest fact that topples Islam is that though it claims to be the continutation of the biblical narrative there is absolutely no record of the mention of Islam before Mohammad. Though Muslims claim that all the prophets were Muslim and that they worshipped allah (al-illah - the god), all our solid, empirical evidence shows us that they were Hebrews and worshipped YHWH, culminating in Christ Himself who revealed in John 8 that He was the manifestation of the great I AM, as God the Son in the flesh (1 Tim 3:16).
I recommended he take a trip to the British Museum to see the artefacts for himself, but he declined and said that he had " a book about that somewhere". Hmm, wonder if he ever did find that book afterwards...
