Martin Luther, in his commentary on 1 Peter 2, writes this about the implication Peter’s declaration that all believers are priests:
A priest must be God’s messenger and must have a command from God to proclaim His Word. You must, says Peter, exercise the chief function of a priest, that is, to proclaim the wonderful deed God has performed for you to bring you out of darkness into the light. And your preaching should be done in such a way that one brother proclaims the mighty deed of God to the other, how you have been delivered through Him from sin, hell, death, and all misfortune, and have been called to eternal life. Thus you should also teach other people how they, too, come into such light. For you must bend every effort to realize what God has done for you. Then let it be your chief work to proclaim this publically and to call everyone into the light, which you have been called. Where you find people who do not know this, you should instruct and also teach them as you have learned, namely, how one must be saved through the power and strength of God and come out of darkness into the light.
Luther’s Works (American Edition), Volume 30, “The Catholic Epistles” pp 65