Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son.
(2 John 1:9 ESV)
Here is the test.
The “teaching of Christ” is, of course, the very word of God.
So, if your preacher is not saying what the Bible says, don’t believe him.
The same would be true for the church. If the church is not saying what the Bible says, don’t believe the church.
If your friends are not saying what the Bible says, don’t believe your friends.
If your own mind is not saying what the Bible says, don’t listen to yourself.
But all of this brings up a vital question. How can you know what the Bible is saying if you are not reading it for yourself?
For us to abide in the Father and the Son, we must be abiding in the word of God.