The eyes of the Lord preserve knowledge, but He overthrows the words of the faithless. (Proverbs 22:12)
The knowledge of the truth is unchanging. Whether it knowledge of history, science or religion. If it is of the truth it will not change. Likewise if we live by the truth, God watches over that truth to preserve it. Truth will always bring doubt to the unbelieving. The soundest truth requires faith. Anything that does not require faith is not of God. Therefore our words must not only be truthful; they must be spoken by faith. And faith demands belief, trust and obedience. Without these elements we do not possess true faith. We must not only believe what we say; we must demonstrate our trust in what we say by living a life that is obedient to the words that we speak. We are not to proclaim what we are not willing to obey. To do so is speaking faithless words. Know therefore of what you speak and speak what you know by faith.