How do we live the life into which we have been born?
In addition to remaining in the Word and the Body, an important step in living the new life is knowing who we are. The language Peter uses here to describe believers is a direct echo of the way God describes the nation of Israel back at Mount Sinai.
When God chose Israel and saved them from slavery in Egypt, He made it clear that their role was to be a nation of priests for the whole world. Their role was to proclaim the greatness of God to the rest of the world and to intercede for the other nations before God.
Israel totally missed this. They mistakenly believed that God had chosen them simply to bless them. Their failure to join God in His mission of calling the world back to Him was their greatest failure.
As followers of Jesus we have been given that role. We are to proclaim the wonders of God; the story of His great love and forgiveness. We are to pray for those around us and call people back into a relationship with God. As a part of that role, we are to behave in a way that brings glory to Him.
There is an important thing to realize about this behavior expectation. We do not live in a way that is pleasing to God in order to earn a new life from Him. We live that way BECAUSE we have been given the new life. We behave in a certain way because of who we are.
Instead, many believers today see their faith through the same mistaken misunderstanding that Israel did. We see our salvation, our new life, as merely a marketplace where God blesses those who please Him. We have a “moralistic therapeutic deism” understanding of Christianity. That is not the Christianity one discovers looking at the Biblical text.