Introduction
For Peter, knowledge is foundational to faith. Often in our Bible reading and study, we fail to note repeated words. I want to help you see "knowledge" as a theme in 2 Peter.
The importance of knowledge, in today's world must not be overlooked. What do you really know? Our world has undermined certainty. We live in a day of relative truth. Knowledge is not possible according to the thinking of many. Here's the first question: What is knowledge?
Knowledge is a key word in 2 Peter, we meet it first in the introduction.

Knowledge In Peter, we are looking at the Greek word epignosis. This is not simply gnosis. This is epignosis. The word has a three-fold significance.

I. Knowledge has a purpose, knowledge equips us, 1:3-4
Knowledge equips us. We do not seek knowledge for the sake of knowledge. I think I'll go to church tonight. Why? I can get smarter. That is not enough. Knowledge must be applied. One can have knowledge and be dumb. I remember a 5th year aeronautical engineering student at Wichita State University who had never learned to drive. Grace and peace come from knowledge.

II. Knowledge should be productive, 1:5-8
To moral excellence we are to add knowledge. This knowledge exists in the spiritual realm. This is not physical knowledge. This is not an admonition to go back to school, to continue our education. This is spiritual knowledge. Phil. 4:8 suggests that as we saturate our minds with spiritual knowledge, we mature, grow into Christ. Our goal is that the pages of our Bible might become dirty so that our lives might be clean. I remind you again of Phil. 3:10. In the introduction to Peter's second letter, grace and peace come from knowledge. This is productive knowledge. The same truth is reflected in 1:9-11. Knowledge is productive when remembered and applied.

III. Some seek pseudo-knowledge, 2:1-3; 3:3-7
Note that our word runs through 2 Peter as a thread. We meet our word knowledge again and again, sometimes specifically, sometimes in concept.
In reading 2 Peter, I often think of the desire to increase knowledge, knowledge toward, in the direction of, toward an object. This is the first definition I mentioned.
In 2 Peter, I can also apply the definition of full knowledge. This understanding of knowledge communicates the idea behind a master's degree. A bachelor originally was an apprentice, ready to study under the master. After studying under the master, one could master the trade, the art, the information. This is our call to master a certain subject, the second definition mentioned above. Christians are called to become masters, not remaining amateurs or apprentices.
Peter is using a word common the lips of pagans, but giving new fullness to its meaning. The Greeks defined sophia, wisdom, as knowledge of things both human and divine. Wisdom was not depth but breadth.
Greeks sought after God and after that knowledge in two main ways (remember 1 Cor 1).
First, they sought it by philosophical speculation. This is the sheer power of human thought. But this has clear, obvious troubles. God is infinite, higher than man. Isa. 55, Job. 11:7. If God is ever to be known, he must be known not because the mind of man discovers him, but because he chooses to reveal himself to man. Further, if religion is based on philosophic speculation, it must always retain the domain of only a few philosophers. Every person cannot become a philosopher. Whatever Peter means by knowledge, it is not philosophic speculation as the Greeks sought knowledge.
Second, some sought knowledge by mystical experience. To be one with the Divine Mystery. Religions of that day popularized this concept. Mystery religions were all passion plays. The initiate was to enter into the experience being depicted. But such experience is transient, temporary.
If the knowledge of Jesus Christ is not be philosophy and not mystical, what is it? In the New Testament, knowledge is personal. I know whom I have believed. Knowledge is ultimately not about facts or things but about relationships and people. Personal acquaintance with Jesus, knowing him as a person, relationship, intimacy. In fact, as you know, in older English usage, the word knowledge was used to refer to the most intimate of human relationships sexually. When Peter says grace and peace come through knowledge, this is not just intellectual, but it speaks of relationship.
Application time. Consider the false teachers of whom Peter speaks. They are seeking pseudo-knowledge, perhaps philosophic, perhaps a popularized version, or an experiential or mystical version, but certainly not the personal knowledge Jesus came to make possible.

IV. Knowledge is not passive, 3:14-16
Another way of saying this: Attaining knowledge is often difficult. Knowledge does not come easy. It is difficult to attain. There is a price.
Illustration: an older preacher was well-versed in Scripture, citing verses without end; a younger preacher said, I would give my life to know the Bible like you do. The older preacher replied, that is what I did.
Knowledge is not passive, knowledge is active. Knowledge is intentional, it requires effort. It is not automatic, by osmosis. You do not sit and listen and gain knowledge. Knowledge involves both the mind and the doing. It is on the job training. Head, heart, hands. Involvement mentally, emotionally, actively. The Old Testament priests read the word, explained the word, lived the word. Doctors are trained by book knowledge, telling others, and practicing.

V. Knowledge is progressive, 3:17-18
The letter closes with the admonition to grow in grace and knowledge. Some have stopped growing. I heard of a well-known brother, he said in debate that he learned the truth 50 years ago and he had not learned anything since. What a statement! How sad.
Knowledge is progressive. Tomorrow I will know more than today. I am growing in knowledge. I am seeking to learn, not just facts, but to know Jesus. I want to know him, his power, his life, his spirit, his plan, his purpose, his eternity.