walikummasalam wa rahamthuallhi wa barakthuhu...
The new website www.ibntaymiyyah.com contains exellent refutations to the doubts of the christains done by Shaykhul Islaam Ibn Taymiyyah. Here are the links
The Correct Reply to the One Who Altered the Religion of the Messiah: Part 1
The Correct Reply to the One Who Altered the Religion of the Messiah: Part 2
The Correct Reply to the One Who Altered the Religion of the Messiah: Part 3
Hope the above helps...