"and how do we know Christ is the last prophet and the Bible is the final authority." -Kevin
Well, ultimately, it isn't something we can prove. Just as, ultimately, Christ being the Second Person of the Blessed Trinity isn't something we can "prove."
But I think the evidence amounts up fairly well. For both cases.
I'll address (briefly) the case you raise. How do we know Christ is the last prophet? Well, this assumes he was sent by God. And if he was sent by God, then what he said was true. And he claimed to be the Son of God. He claimed to *be* God.
And then, he claimed to build a church (singular) which would last until the end of time.
"He said to them, "But who do you say that I am?" Simon Peter said in reply, "You are the Messiah, the Son of the living God." Jesus said to him in reply, "Blessed are you, Simon son of Jonah. For flesh and blood has not revealed this to you, but my heavenly Father. And so I say to you, you are Peter, and upon this rock I will build my church, and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of heaven. Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven." -Matthew 16:15-19
There is no reference to future prophets, as always present in the Old Testament there is a reference to the coming of the Messiah.
All of the prophets of the Old Testament were but foreshadowing the Prophet of the New. Even John the Baptist, Christ's cousin was preparing the way for the Lord.
So it doesn't seem to follow that there would be yet another prophet *after* Christ (although this is the belief of Mormons with regard to Joseph Smith).
After Christ, came the Church which he established to guide and protect his flock. He tells Peter, "Feed my sheep...Feed my lambs...Feed my sheep." -John chapter 21
Peter died, but passed on the duty of shepherding Christ's flock here on earth to Linus. Who died, and passed it on to Cletus. Who died, and passed it to Clement...down to John Paul II who died and passed it to Benedict XVI.
You can find the full list here:
"hypothetically, any of the "recent" churches could have been created directly by God to supplement his previous teachings. so even if they are radical, we cant say for nsure they are incorrect" -Kevin
But such a claim would fly in the face of Matthew 16:18 (quoted above) where Our Lord himself says, "the gates of hell will not prevail against [my church]."
A church that claims divine origin has to also claim the church Christ founded collapsed (incidentally, this is the belief of the Mormon church).
But it seems to me, that to believe that, you have to believe Our Lord was either a fool (for making promises he could not keep) or a liar (for making promises he could not keep). I reject both conclusions.
"and for some of the older teachings, its possible the've been lost in translation from the past..how do we knoew this is what was originally taught..over 2000 years its pretty safe to say teachings will change" -Kevin
Then everything gets called into question and no one nor anything (including the Bible) is to be trusted.
But history shows that there has been only one church since the time of Christ: the Catholic Church.
Christ founded it, so I'm in. I don't want to be a member of a church founded by any man or woman. I want to be in the one founded by God himself.