The dull retort, “You think you know everything,” is an exceptionally not-very-bright response to a challenge of one’s beliefs. Unfortunately, that is about all some have to fall back on when they have exhausted everything else and are still found in conflict with the plain, simple Word of God. The odd thing about it is that people often use this statement as if it is the end-all of all arguments, disagreements or conflict, as if… it makes sense.
God certainly says: “The secret things belong unto the LORD our God,” but in the same verse He also says, “but those things which are revealed belong unto us and to our children for ever, that we may do all the words of this law” (Deuteronomy 29:29, KJV). Plainly, some things were revealed and God expects us to know and do what we know (Romans 14:23).
To argue that, because we do not know everything, we can know nothing, even contradicts Jesus. In a rather heated dialogue with a Jewish audience that ended in their attempt to stone Him, Jesus stated: “And ye shall know the truth, and the truth shall make you free” (John 8:32, KJV; evidently, knowing the truth was not high on their to-do list). Jesus claimed that we could know that which God has revealed and discern the fact of its truth, which implies that we also have the ability to recognized and label, by contrast, that which is false (2 Peter 2:1).
What we need to know, we can know. What is beyond revealed knowledge most often has a more to do with how much time we spend in God’s Word (2 Timothy 2:15) and how willing we are to submit to the simplicity of God’s Word (2 Corinthians 11:3); “those things which are revealed belong unto us” implies we must know our Bible.
Finally, there are some things we will not know because God has not revealed them; but God does not hold us accountable for and does not expect us to know those things. What is revealed is that for which we will give an account.
Hosea would complain, “My people are destroyed for lack of knowledge” (Hosea 4:6). Such is the sad plight of those who prefer ignorance or reject Divine revelation. No one knows everything but we can know something; and that something will make the difference as to where we spend eternity.