By mentioning faith at the beginning of his list, Peter is telling us what is needed for our faith to be healthy and strong. Our faith has been given to us by God (2 Peter 1:1) along with the righteousness of Christ, and now we must pursue virtue in order to strengthen our faith. When we act like Christ (pursuing virtue), we strengthen our faith in Christ and keep ourselves from following the lies of heretics.
5 For this very reason, make every effort to supplement your faith with virtue, and virtue with knowledge,