The Scripture is clear regarding the replacement of Judas Iscariot and his office among the twelve disciples. Paul was not and could not have been considered the replacement for Judas since he did not meet the qualifications for the task.
Replacing the empty office
Before the day of Pentecost, Peter led the believers in replacing the twelfth position left empty by Judas’s betrayal of Jesus. In Acts 1:20 Peter explains from the Psalms how that there was a necessity to fill the position left empty by Judas’ ‘transgression’ (Acts 1:25).
Peter subsequently lays forth three qualifications that would determine who was eligible for such a lofty position.
He explains:
The new apostle would be given the authority of the remaining eleven in being witnesses of the ministry and resurrection of Jesus. As such, they were required to:
The exact number of people that fit these three requirements is unknown, but the disciples appointed two who obviously passed the tests – Barsabas and Matthias. What can be known is that Paul did not meet any of these qualifications.
After prayer and casting of lots, Matthias was ordained the twelfth apostle and witness.
Peter’s authority
Despite this account within Scripture, some would continue to insinuate that Peter made a mistake and should not have appointed Matthias. Therefore God raised up Paul to be the twelfth man.
However, we should remember that before Jesus’ ascension he gave Peter the keys of the kingdom of heaven:
Also Jesus’ taught the disciples the rule of two:
Not only so, but through their prayer and the promise provided by Jesus himself the disciples could have expected to see God’s approval in the appointment process.
So then, there seems to be no Scriptural reason that Peter made a mistake in numbering Matthias with the eleven.
Paul’s ineligibility
Peter had authority from Christ to appoint the twelfth apostle. He ordained Matthias, because he met the qualifications and was chosen through prayer and the lots (Acts 1:24-26).
Paul, on the other hand, did not meet any of the qualifications of being numbered with the eleven. Furthermore, at the time of the Pentecostal appointment, Paul, who was then called Saul, was among those persecuting the followers of Jesus!
Scripture testifies to these facts even seven chapters after the appointment of Matthias and the Holy Ghost empowerment:
“And Saul, yet breathing out threatenings and slaughter against the disciples of the Lord…” – Acts 9:1
It is obvious that Paul did not accompany the disciples throughout Jesus’ ministry, for if he had it would have been as a persecutor.
Nor did Paul subscribe to the ministry of John the Baptist and his baptism. Paul, according to the law a Pharisee, may indeed have been one of the many to whom John cried out ‘O generation of vipers, who hath warned you to flee from the wrath to come?’ (Matthew 3:7).
Finally, Paul in no way participated in the witness of Jesus’ resurrection or ascension as he first saw the resurrected Christ ‘last of all’ after he appeared to the apostles.
In the end, there is no Scriptural evidence that Paul could be considered for an office among the Disciples under the Scriptural requirements set forth by Peter. The apostleship that Paul was given had to be a separate apostleship, testifying of a different ministry than that which was testified by the leaders of the Jerusalem church (Gal 2:7-8).