Perhaps the best way to answer that is the bible is not up to a "theists interpretation" as many people try to argue.
One cannot claim that the book is the Word of God and then say that it is open to our interpretation. Surely, if we believe God to be perfect, then every word he says is perfect and spoken for a reason. For us, an imperfect people, to interpret what I think the bible means would mean i'm corrupting God's Words.
In that sense the bible should not be interpreted.
But how then does someone understand what God wants to say? If it is God's interpretation, then only God can interpret it right? Right.
I cant speak for other religions but I know that Christians believe God gives them the gift of his Spirit to dwell in them. The Spirit is a guide and a councellor who uses the word of God to teach us. And since he is God, he is capable of interpreting the word of God. Therefore it is not the Christians who should be doing the interpreting.
But that begs the question: Why do christians believe in differing things? And if they all have this same Spirit, why are there so many different churches who disagree with each other?
The only way I can explain that is that Christianity has core values which the Holy Spirit convicts us of. Stuff like Jesus being the sacrifice for our sin and being the Son of God etc.
On top of that are issues that arent necessary for salvation and as such Christians usually make more of a personal conviction about that. These are things like God choosing Christians, and people being born naturally sinful. They are cool things to think about, but in the end dont lead you any closer to salvation.
If you look around most bible based churches (places where the God's word is taken as authority) you will find they generally believe the same sort of stuff. That is because they believe that these are the perfect words of God and that the Holy Spirit teaches us using these words.
Its when people start interpreting their own ideas from the bible or when they don't even look to the bible at all that you start to get lots of weird crazy stuff being thrown around. I would not go so far say such people have not recieved the Holy Spirit, but the Spirit uses the words of God to teach us. And if we are not studying the words of God then we're not going to let him teach us much are we
It is our human nature that causes the divisions in the church. We would rather be proved right about the little things than worry about all christians being up to date with the important things. And as such Christians look silly from all angles.
The people who have good theology argue with the other churches who have good theology, and the people who have bad theology look stupid because they have bad theology.
But in the end it doesnt matter (well it does matter if Christians dont read the bible!), but it's the salvation issues that the Spirit convicts Christians of that really matter.
Sorry for the long winded response but i guess i wanted to answer a pre-emptive question while I had time