(Kristevon) "Do you believe you have to confess your sins to a priest to be forgiven? Do priests have to confess their sins to another priest to be forgiven??"
(Cristoiglesia) Christ instituted the sacraments purposefully. The sacrament called reconciliation or penance is what we call our actions when we go to confession. Going to confession and confessing to a priest is the normative way of reconciling oneself back into God's family when we have committed a mortal sin. It is the biblical way corresponding to Jesus' teaching as recorded by the apostle John in John 20: 22-23. What we learn from John is the authority given to the priests is not only to forgive sins but also to retain sins. Jesus commanded the authority to be used. It is the duty given by Jesus for the priest to measure the contrition of the penitent and act accordingly.
However, one must repent and pray sincerely to God as an act of contrition before one enters the confessional. The priest represents Jesus by acting in persona Christi and for the entire family of God represented by the Church militant who is harmed by the sin of another. No sin is private but all sin affects others. Jesus described this relationship as a vine with Him as the vine and we as the branches (John 15:5). If one member of the branch is sick then all
the branches are affected and suffer as a result. Because of our familial relationship with each other Jesus created a means of confession so that all those affected in His family are represented by the priest as is God. The acts of sin and forgiveness are not private matters. God bless!