Whose Doctrine?

I am, unfortunately, aware that some of our brethren are advocating the idea that anyone who professes to believe in God and who may or may not have been baptized must be accepted as brethren.  Even in the church, some are saying that there is more than one path to God, that man is free to approach God in the way that seems best to each man.  I must admit that I cannot agree with that philosophy.

In Matthew 7:13-14, Jesus inform us that the way to Heaven is strait and narrow and not many will find it, but many will follow the broad way that leads to destruction.  Sorry, but that does not sound to me like just any way will do.  In fact, it seems to me that, in Matthew 7:21-22, Jesus specifically says that simply saying you belong to Him will avail you nothing if you do not follow His teachings.

Now, I want you to read closely I Timothy 4:1  But the Spirit expressly says that, in the latter times, some will depart from the faith, giving heed to seducing spirits and the teachings of demons.”  Here is my point:  If Jesus says that many will be lost because they do not strictly follow Him, and the Holy Spirit says that anything not following New Testament teachings if the doctrine of demons, how can it be possible that any deviation from the plan given to us by the Holy Spirit can possibly save man?

What say ye?