During a conversation about possible paths to salvation, my wife pointed out to me something I hadn't thought of before - that declaring Christ your sovereign is not only a Biblical prerequisite for salvation, but it is also a logical one. That is, if we view salvation as participation in the new heavens, new earth, and new Jerusalem, which is under Christ, then, as a necessary precondition for being in this new kingdom, one must first assent to the King, which is Christ.
This isn't to say that it is logically necessary that this must happen before death (though I think one can say so Biblically, at least for the most part), it is logically necessary that this must happen before salvation. If someone has not assented to the Lordship of Christ, then their faith is inadequate for admission to the kingdom, for they have not yet acknowledged the King. So for one to say that all faiths are equal paths to salvation, I think logically this is incorrect. If Christ is King, then there is one path into the kingdom. Perhaps the other paths lead you to the gates, and even participate in activities which are similar to those in the Kingdom. But in order to fully enter in, one must pledge obedience to the King. For a Christian, this has already occurred, and therefore they are already within the Kingdom. But for one who isn't, even if the possibility of salvation is offered after death, admission into the Kingdom isn't possible on earth unless they acknowledge the King.