It is all continuation of history. Even the current kind attention of the western forces towards Islam has smooth link with the crusadist past. The west has broken its relation with Christianity to some extent, which in itself is a tragedy, but the attitude towards Islam and hence the Muslims remains the same one.It is sad how the West hasn't taken the time to get to know the Prophet (saw).
See he was a Muslim so that is expected. The trouble is that he could not over come perennial philosophy. He thought it was some thing good. That is bad but then how many of us can assert that we have overcome our own prejudices?Which was why I was surprised at the amount of knowledge Lings had and how, often times in the book, he defended the Prophet (saw).
I seem to remember that in Martin Lings biography of Sheikh Ahmad Alawi (ra) perrenialist ideas crop up a few times, at one point he wrongly interprets (i.e. misunderstands) the Sheikh's words to imply perrenialism, however the Sheikh was obviously telling him that they must have the correct aqeedah (written as doctrine in the book, I think), but Martin Lings could seemingly only hear this through the filter of his pre-existing ideas. Anyway Martin Lings was a nice old man and I hope and pray that Allah accepted him and overlooked any faults that he may have had.
Perennialist Assertion : All the existing religions in their present form are correct and legitimate path to salvation.
Remember Allah (SWT) does not like deviation in the least bit.