In John 17:17, as Jesus prayed to the Father, He said, “Sanctify them in the truth; Your word is truth.” Notice that He didn’t say, “All truth is your truth.”
During the past several years, the church has been passing around this little cliché that says, “All truth is God’s truth.” Some will probably wonder, “Well, what’s wrong with that?” The problem with that thinking is that the assumption behind it is that there is some type of valid truth about man that is found outside the Word of God.
When the people who promote that idea talk about it, they are not using that cliché to refer to things such as mathematics or physics. They aren’t saying, “Well, it’s true that 9 x 9 = 81, and that truth is not found in the Bible.” If that was what they meant by what they were saying, I would agree with them.
But when they say “All truth is God’s truth,” they are using it to refer to truth about man, his nature, and character. In other words, they are endorsing the psychologists who claim that the things they have “discovered” about the character of man which are not found in Scripture are true and that it is God’s truth.
That goes contrary to the basic, foundational reality of the Word of God, and we don’t need to fight that battle. God’s Word is sufficient. 2 Peter 1:3 tells us that we have “everything pertaining to life and godliness,” so we don’t need to be mixing human wisdom with divine wisdom. Psalm 19:7-11 explains all of the benefits of God’s Word for the believer, and then Psalm 119 pours out the summation of all that the Word accomplishes for those who depend upon it as their source of strength and wisdom for this life. All we need to know is that only biblical truth is salvation truth. Only biblical truth is sanctification truth. You can’t take biblical truth and mix it with human wisdom and claim that the end result is all truth.
But many people who haven’t thought through these issues are not prepared. They are, in effect, lured into danger like a naïve child can be lured by a stranger. They haven’t carefully considered and kept before them this basic, foundational matter—that we know and have been established in the truth, which is the faith which was once for all delivered to the saints. And as a consequence, all kinds of corruption have infiltrated the church under the slogan, “All truth is God’s truth.”
Beware! Unless you can find what is being taught clearly spelled out in God's Word, don't receive it simply because someone claims it is true. Human experience is never the standard for truth. Only God's Word can meet the standard of perfection.