On one occasion at Speakers' Corner in Hyde Park, one of my friends was discussing Tawheed with a Christain who was attempting to (and as always, quite poorly too I might add) defend the Trinity. Unlike other Christains, Jehovah's don't believe in the Trinity so my friend approached one of them and told him that one of the Christians is propogating the doctrine of the Trinity and claims that anyone who does not believe in it is not a Christain, so the Jahovah guy marched up to the other Christian, shocked us all by pulling out one of Shaykh Ahmad Deedat's (rahmatullahialayh) books and then refuted him with the book right there and then! That was a sight to behold I can assure you of that. We laughed about it all the way home.