Doctrine

(as it is used in this verse),
means,

The truths and principles
taught by Jesus Christ
and His apostles;
also, instruction
in the gospel.

All scripture is given by inspiration
of God, and is profitable for doctrine,
for reproof, for correction,
for instruction in righteousness:
that the man of God may be perfect,
throughly furnished unto
all good works.

2 Timothy 3:16 and 17...