Agabus was apparently a well-known prophet in the early Church. While we don't know very much about him today, two of his prophecies are mentioned in the book of Acts. Those two prophecies are at the very center of an old debate about whether or not prophetic ministry differs between the Old Covenant and the New. Specifically, the question is raised as to whether or not there is room for mistakes in prophetic ministry in the New Covenant.
Knowing God involves more than the simple knowledge of truth. It requires a personal and emotional experience. It depends on a mutual exchange. Truth is good, but not alone. Understanding the ways of God is good, but it's not enough. Knowing God is about relationship, and relationship only exists within the context of ongoing personal encounter, shared experience, and emotional interaction.
I have a whole new life in Christ. But if I don't understand what that means, then I will wander through life with a case of mistaken identity. When I gave my life to God, I died and was raised to a new life. I am now hidden in Christ and He defines me. If I don't know who God says I am, then I am essentially carrying around a false I.D., trying to be someone that I am not. If I embrace my new identity, I naturally begin to grow up into my new life in Christ.