There will always be people who teach their own ideas, but the Word of God is sure and certain.

2Ti 2:14  Of these things put them in remembrance, charging them before the Lord that they strive not about words to no profit, but to the subverting of the hearers.

15  Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.

16  But shun profane and vain babblings: for they will increase unto more ungodliness.

17  And their word will eat as doth a canker: of whom is Hymenaeus and Philetus;

Paul gives Timothy a warning and direction here, and it is based around following the things of the Word of God, and not the teachings of men.

Paul has already given a lot of teaching for Timothy and in this section he tells Timothy to put the people in remembrance of these things – the things he has taught.
Then He says to Timothy that he needs to study – this is in particular the study of God’s Word, and it is in contrast to the striving about words, and the vain and profane babblings.

This is the real point of this – for someone to be a workman that needeth not to be ashamed, he must do two things: study the Word of God, and not to strive about words to no profit.

The first and most important part of this is the study of God’s Word.

You do not have to study all the many, many, many false teachings out there. In fact, it would be impossible for any man to have enough knowledge to be up to date with every false teaching.
There is value in being aware of the main errors, but the greatest value is in knowing the truth so thoroughly that you instantly recognise the false.

It is a well worn illustration, but apparently, when training bank cashiers, they don’t tell  them what counterfeit money looks like – they give them real money and get them totally familiar with the real thing. Then when a fake passes through their hands they instantly “know” something isn’t right – they may not know straight away what is wrong, but they instantly know that they need to stop and look closer – it doesn’t fell right in their fingers, it doesn’t look quite right, it may not smell quite right – something is not right. So they look closer – they study the note, looking for the vital signs of truth they have been taught – and they see the problem.

If you know the truth well through your study of the truth, then when someone comes with a false teaching, you may not know immediately what is wrong with it, but you know instantly that something is wrong with it.

And you know this because you have studied the truth from God’s Word.

On investigation and comparison with the truth from God’s Word, you can see that the words that are being passed off are in fact vain and profane babblings – not from God at all.

And that if these words are followed they will lead to spiritual sickness and death.

I will just add in here that the first verse I quoted says “….strive not about words to no profit, but to the subverting of the hearers.”

We need to not get into a debate with people who bring in false teaching, for they will twist and turn things, and sometimes they are great debaters. They are often skilled at arguing their position, and can run rings around most people, by twisting and turning words, and shifting the subject before a resolution can be found.

We are not to engage in this kind of unprofitable talk, for it will cause you to doubt when you can’t “win the argument”.
This doesn’t mean that we are to let people get away with false teaching – but we are to keep on the point, and not get sidetracked and turned around in the discussion.
Keep bringing them back to what the Word of God says on that issue, and don’t let them drag you into other subjects until the Word of God has prevailed over their worldly philosophies.

Above all else remember that in such discussions it is the knowledge of the Word of God that is of utmost importance – don’t debate on what they think or what you think – stick to the Word of God.

After all:
Heb 4:12Heb 4:12
English: King James Version (1611) - KJV
12 For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.  

WP-Bible plugin  For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.