True belief that lives by faith follows in the steps of Abraham.
True belief that lives by faith recognizes their sinful state.
True belief that lives by faith repents.
But is belief all there is? It depends on what you think the definition of belief is.
Was it enough to be able to commune with only Him or did I think I needed more?
Does the Holy Spirit dwell in you? If I asked you that question, how would you answer?
The point is, Peter is writing to Christians who were being terribly persecuted by evil, disobedient men and they needed encouragement and confidence in enduring these trials. What could give them that?
To love Christ is to love His people.
What proof would we give if we must believe He is risen without seeing the very marks on His hands?
If we have not obeyed in the way God has instructed, can we expect to receive what God has promised?