An old peril now bigger
Choosing what we want to hear is a peril as old as the hills. Paul warned of those who would listen only to people who told them what they wanted to hear (2 Timothy 4:3). He was speaking to a young pastor and forewarning him that the day would come when someone would stop coming to hear him because he was offended by his teaching, and instead this person would gather around himself teachers that told him what he wanted to hear.
The end effect of neglecting the pastor's sound doctrine, said Paul, would be they would turn from the truth and start to believe myths!
Today this peril is made more real by the internet.
You can google your favourite subject and end up strolling down an infinite and narrowing corridor of ideas with which you agree. That's the point, "with which you agree." There you are, all on your own, following your own self, your own weaknesses, your own foibles, your own ideas. You following yourself. You disicpling yourself.
So if you are a judgemental type you could find some website that will condemn virtually all Christians (except yourself). If you are a lovey-dovey type, you'll find a website that never mentions hell. If you're a hell and brimstone type, you'll end up listening to "sock it to 'em bro" sermons.
No-one to correct
There'll be no-one to correct you, to point out that the corridor you have chosen is getting narrower and narrower. Eventually you end up believing myths. Stuf so far removed from the Gospel that Paul calls it "myths". Nothing to do with Jesus, nothing to do with God, nothing to do with the grace, nothing to do with the Gospel.
Why we can't grow on your own
There are five reasons we cannot grow as a Christian all on our own:
First you were never designed to learn (or do anything) on your own. God made us in his triune image and that has life-shattering, all-encompassing implications - including on how we learn. None of us have enough wisdom, experience or sense to learn on our own. It is never good for any man or woman "to be on their own" - for anything.
Second, the image God gives to believers, is of a body, in which we are merely one part. No-one is more than a body part, eye, ear, whatever. It's actually impossible for any one body part to function without the others - at any level, including growth.
Third, we are fallen, so we all have profound imbalances. Someone who tries to grow on their own, will end up a monstrosity, with only certain areas growing and others completely neglected. A child given the choice to eat whatever he wants will end up ill, because there is something they need, which they won't eat. They'll end up with spiritual scurvy.
Fourth, God has given pastors to teach the whole counsel of God. The purpose of elders and pastors is to feed the flock a balance of the whole counsel of God, as Paul did in Ephesus (Acts 20:27).
Fifth, the Bible specifically says that growth is a corporate activity (Ephesians 4:16). The body grows, that's the unit of NT growth. The idea that we can grow in isolation from the body belies an OT or monkish ecclesiology.
And example of growing through others
Every wise preacher consults commentaries. In this way they are not preaching what they think the passage says but listening to the collected wisdom of centuries and even millenia of faithful preachers- who of course, in turn, prayerfully asked God what he was saying. This is how we get wise - surround ourselves with a multitude of wise counsellors.
A wise preacher will deliberately buy a range of commentaries: some of his own theological bent and others of a different bent. He may even buy (or in this case better borrow, so that he does not waste money) liberal commentaries so that he can see how the pagan in the pew might be hearing that passage (a liberal is someone who approaches the Bible as one might approach Homer or Shakespeare, with no faith, no respect and no spiritual understanding - very helpful if you are preaching to pagans so that you can hear what they'll be thinking about the passage).
An example of stilted growth without others
I remember hearing about a meeting between a great Christian leader in the UK and a Christian who had been tortured for Christ over many years with many years on his own in prison, in solitary confinement. What was that Christian like? Well he had become weird. Who wouldn't become strange? In this case it was not his desire to be alone, but aloneness had twisted his personality and to some extent even his theology. The Great Shepherd of the sheep kept him in those dark years, but isolation was not an ideal place for developing doctrine or spiritual life.
Me, my Bible and God
An indaquate method of spiritual growth is to sit in our rooms and read the Bible in splendid isolation from everyone else. Thinking we are hearing the Lord, but in fact being unaware that half the voices we are hearing are the loud voices of personal prejudice.
The very best way to grow is to listen to preaching addressed to our own community by a wise, loving and courageous pastor and through shared Bible Study with fellow believers where our prejudices and foibles - and frankly sinful and foolish ways of thinking - are constantly being exposed and addressed.