"His divine power has given us everything we need for life and godliness through our knowledge of him who called us by his own glory and goodness." NIV translation
We have everything that we need to live for God and to be a light in this world. We are reminded here that it is only by God's calling us that we came to accept His grace as we would not have even looked for Him on our own. When He called us, He also gave us the Holy Spirit which gives us the knowledge of God's will and the power to live the Christian life and to glorify God.
We have the Bible and the Holy Spirit living in us and so we know of the promises that God has given us. Through those promises, we know that we will be with God forever and that He is in fact in us through that Spirit. Through the Spirit, we have overcome the evil of the world.
"For this very reason, make every effort to add to your faith goodness; and to goodness, knowledge;" NIV translation
Because God has called us to be saved and to honor Him with our lives, we are to grow in our walk with Him. Peter begins a list of areas we should work at growing in but we must realize that it is only through the very power of God that our growth is even possible. He says to add goodness to our faith but this goodness is not like we think of it. This would better be translated as "courage" rather than goodness and it is speaking to the fact that we should continue to grow more bold in our ability to declare the Word of God to the world even when it starts to cost us things.
"and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness;" NIV translation
We are told to add knowledge to our faith but this means more than we think. When we think of knowledge, we probably think of learning more facts and storing them in our brain but this is different. This is talking about epignosis or a super knowledge where the heart is changed by Jesus Christ. On top of that knowledge we are to add self-control and for most of us this is a pretty obvious one. This is simply where we don't do things that we would like to do because they would not honor God. Through Christ, we have the power to control ourselves. Next is perseverance which is often associated with patience in dealing with things and other people but this is actually talking about endurance. It speaks to being able to endure hardship (persecution) because of your faith and to react in the same way that Christ did when He forgave those who crucified Him.