Protestant
Doesn't 1 Peter 2:9 mean there's no need for ordained priests?
The 'royal priesthood' of all believers describes every Christian's share in offering spiritual sacrifices through baptism, but it does not eliminate the distinct ministerial priesthood Christ instituted at the Last Supper for those he ordained to confect the Eucharist and forgive sins.
Catholic teaching
The Church distinguishes the common priesthood of all the baptized, who offer their lives as spiritual sacrifice, from the ministerial priesthood conferred by holy orders, through which Christ acts in the person of the Head to confect the sacraments — a distinction of kind, not merely degree.
Biblical foundation
At the Last Supper Christ commands only the Twelve, 'do this in remembrance of me' (Luke 22:19), and gives them alone the power to forgive sins, 'whose sins you forgive are forgiven' (John 20:23), establishing a specific ministry distinct from the general priesthood Peter describes for all believers.
Scripture references
Historical evidence
Ignatius of Antioch, writing around AD 107, describes bishops, presbyters, and deacons as a settled threefold ministry distinct from the laity in every church he addresses, showing the ministerial priesthood was universal apostolic practice, not a later corruption.
The Church Fathers
“Apart from these, there is no Church.”