Which is best, or which is correct?
Does one study a particular text to determine what is overall Biblical doctrine?
OR
Does one use overall Biblical doctrine to determine the meaning of a particular text?
My answer: Its always best to look at the bigger picture. Because the Bible contradicts itself a lot, and im not saying this as an error, its done on purpose, (NOTICE english isnt my native language so maybe there is a better word to use here but i cant think of any). For example:
Eze 18:31 Cast away from you all your transgressions, whereby ye have transgressed; and
make you a new heart and a new spirit: for why will ye die, O house of Israel?
Eze 36:26 A
new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
So God gives you the heart, and you got to do it yourself. This is where you got two sides going at it: One side is quoting the first, the other side is quoting the latter.
Many times things like this are in the Bible, thats why we got so many different doctrines and churches. Here is another example:
1Jn 1:8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
1Jn 3:6 Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him.
So if you dont admit you have sin, you dont have truth in you and are self-deceived. BUT if you sin, you havent even seen God nor known Him. The same thing in John's epistles is where it says "I write that you sin not, BUT if any man sin, we have an advocate with the Father" but at the same time: He who sins is of the devil...
These are just a couple of examples, but there are a ton more. If you take just ONE of these verses and discard teh other, you can come up with all kinds of weird doctrines! Thats why the WHOLE BIGGER PICTURE is key imo!