Knowledge of God Is Exclusive to Christians

This sounds pretty inflammatory, only Christians can have knowledge of God? How dare we think like that? Well, for one reason, Jesus told us: 

All things have been handed over to Me by My Father; and no one knows the Son except the Father; nor does anyone know the Father except the Son, and anyone to whom the Son wills to reveal Him. (Matthew 11:27)

That's an important verse, and an important concept: "nor does anyone know the Father except the Son, and anyone to whom the Son wills to reveal Him." Jesus tells us flat out that only He knows God The Father, and He chooses to whom He will reveal that knowledge. This entire verse is keeping with the ancient law or custom known as the Jewish Law of Agencies. This simply states 

"A person's agent is regarded as the person himself." Therefore any act committed by a duly appointed agent is regarded as having been committed by the principle." (The Encyclopedia of the Jewish Religion, R.J.Z. Werblowski and Geoffrey Wigoder)

So to know Jesus is to know God, which is what Jesus stated. Christians know (or strive to know) Jesus. We love Jesus, we follow him, we cling to his every word. We talk to him in prayer, we give him praise and glory and we try to emulate him as a little brother would copy the thought, word, and deed of a much older, wiser brother. As we do this we learn about God. 

When our Coexist friends start preaching their "All Paths Lead To God" screed, their rhetoric should bring a tear of sadness to the Christians eye. These people reject Jesus, so how can they know God? And why would they preach such unsubstantiated stuff? It's more than likely the god of this world putting ideas into their heads.

3 And even if our gospel is veiled, it is veiled to those who are perishing, 4 in whose case the god of this world has blinded the minds of the unbelieving so that they might not see the light of the gospel of the glory of Christ, who is the image of God (2 Corinthians 4:3-4)