Since Jesus made this statement in the context of "on this rock I shall build my church" someone could say that the authority to bind and loose was not given to Peter but to his church. This point of view can be defended by referring to John 20:23. However, when he spoke to Peter, "you" was in the singular in Greek. That is also how it is translated in other languages.
Nevertheless, Peter's fallibility was demonstrated moments later when Jesus called him "satan" (Matthew 16:23). His authority was therefore dependent on his being "in the Spirit". When he was "in the flesh" Peter was advancing the agenda of satan.
That same authority was given to the 10 apostles after Jesus had re-commissioned them and breathed on them (John 20:21-22). On this occasion they received the Holy Spirit and were authorised to forgive anyone's sins or to withhold forgiveness. No-one who has read church history with an open mind can deny that churches have abused their authority too many times to count. My conclusion is therefore that the authority is dependent on "being in the Spirit", however mysterious that may sound.
Power was also given to the apostles by the Holy Spirit. However, they only received Holy Spirit power 50 days after Jesus had ascended into heaven (Acts 1:8; 2:1-4). When a person repents of sin and receives forgiveness through faith in Jesus because of his undeserved sacrificial death, that person receives the Holy Spirit, just like the apostles did when Jesus breathed on them. Nevertheless, the apostles, Samaritans and the Ephesians received the Gift of the Holy Spirit "a second time" (Acts 2:4; 8:14-17; 19:6). In the same way modern day believers who desire God's power to do good can ask Jesus to baptise them with the Holy Spirit (Luke 3:16).
