So how will you know when you reach that correct understanding?
I only need to have a correct understanding of scripture from a salvation point of view - i.e. what do I actually need to understand from scripture which will allow me to respond to the gospel message accordingly.
I think I'm pretty clear of what this is.
The common areas of division/ disagreement over interpretation of scripture are normally on things on which salvation is not dependent on. For example:
Creation
Pre/post or amillennialism
Pre/ post/ mid tribulation rapture
Dispensationalism
Related areas of calvinism
Related areas of infant baptism
These are intramural differences, and for the most part our salvation is not dependent on holding a position on these either way..
There may be certain Bible passages tucked away somewhere that ultimately I may never study or fully understand, but since these are not salvation dependent then this is less important - or arguably even unimportant.
The central message and purpose of the Bible is what matters here - the gospel message of salvation and we should respond to it.
So it's when the ideas and beliefs which central to salvation are tampered with and distorted by JW's and such like is when the differences become so huge that they result in the formation of a sect, cult or completely new religion being formed.