The Jehovah Witness Issue

So, I'm currently studying and praying through some of the doctrines of the JW to prayerfully get to the crux of the matter with them. My first and main question is: WHY does it matter that they do not accept that Jesus IS God incarnate?

This was bothering me during my quiet time this morning........because they are SO DANG close to orthodox Christianity, that they call themselves Christian............but rejecting the doctrine of the Trinity is just kinda fruity, since it has always been understood as part of the dogma for the faith. To me, the question of WHY could be asked about many doctrines that I believe are critical........(doctrines of Grace).........WHY does it matter that someone understand that doctrine? DOES it matter?
I know many believers who cannot get that paradigm to shift.......but I know they are true believers by their fruit.....so, I don't believe I need to pull at that thread.

I got to thinking more about how other faith's are SO close to the truth......but just off enough to be heresy.
ie...Islam.
They believe that Jesus was born of a virgin named Mary.....they believe that he was sent by God....but that he was not God....nor do they believe he was the Son of God.......nor do they believe that he died on the cross, but they think that somehow Judas Escariot traded places with him......(sigh) but they think he was just a prophet....sure, a sinless one, but a prophet only.
Their book calls him the "messiah" something like 23 times, but they do not have any idea what he is the 'savior of'
Instead, they believe that God will somehow weigh their good and their bad and if they have more good than bad, they might be given mercy. (if they "earn" it) yikes.

The next super super close call is Catholicism.
Having been raised in the faith, this issue is close to my heart.
They believe in the trinity; they believe Jesus was God; They believe all of the tradiitonal dogma......BUT they believe the church (the popes) have the authority to interpret scripture alone..(even though Paul called the Bereans NOBLE for going home to read the texts to "see if the things were true" that were said by the apostle himself.)
They hold up tradition as if tradition is authoritative.......and they mingle Christ with other things like mysticism.....and the praying to his mother to get his attention. (see book entitled "doctrines of Mary")
I've been listening to sermons by MacArthur lately about the catholic church's standings on Mary and other issues. (whether a devout catholic would say they believe and follow the catholic church's stance on the issues is another thing)
It's incredible to me the pride one can take in a banner like "catholic" and love their sin almost as much.
All in all......many catholics that I know believe that if you're baptized, and you never murder anybody, God will let you into heaven. Others that i know who are more devout believe that Jesus + good deeds will get you into heaven.
Both are dangerous positions to take. I hope to be writing myself silly about these topics......(since writing helps me to sort through my thoughts)

Anycrap....if I have offended you and you are muslim or catholic......please know that is not my intent. My hope in the next few weeks of studying is to gain a better understanding of scripture...and to post what I find. The WORD is the authority, not me k.
So, if you think I write something that contradicts scripture, email me or post a comment....I promise I read them all, even the ones too profane for me to publish.

My goal is God Himself, at any cost, my dear Lord.
Jen2