"Your man has been accustomed, ever since he was boy, to have a dozen incompatible philosophies dancing about together inside his head. He doesn't think of doctrines as primarily 'true' or 'false,' but as 'academic' or 'practical,' 'outworn' or 'contemporary,' 'conventional' or 'ruthless.' Jargon, not argument, is your best ally in keeping him from the Church." C.S. Lewis in The Screwtape Letters
Doctrine, not jargon, will lay a solid foundation for the believer. Learning doctrine is essential for the believer to be informed in both how to live as much as what to believe to live. Doctrine is practical, and practical material must be doctrinal if it is to be of any help at all.
So why, pray tell, do so many believers run from the study of doctrine? Because she thinks it only "academic" but not practical, because she thinks it only "outworn" but not relevant to today, or because she thinks it only "ruthless" and not conventional to what she's always believed? Because she has embraced jargon to avoid argument and is content to call that doctrine.
From whence does solid doctrine come? And are believers really tasked to learn solid doctrine and then also to live according to solid doctrine?
"If you put these things before the brothers, you will be a good servant of Christ Jesus, being trained in the words of the faith and of the good doctrine that you have followed." 1 Tim 4:6 (ESV)
"Watch your life and doctrine closely. Persevere in them, because if you do, you will save both yourself and your hearers." 1 Tim 4:16 (NIV)
"He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it." Tit 1:9 (ESV)
"But as for you, teach what accords with sound doctrine." Tit 2:1 (ESV)
Only true Biblical doctrine can inform a believer against the world's jargon. If she knows not only what she believes but why she believes, then she will have no fear about being asked questions, and her answers will comprise more than a hollow "that's your opinion".