Why was Matthias chosen to be the 12th disciple?

The Bible gives the criteria.One of the reasons Matthias was chosen to be the 12th disciple was for the purpose of having 12 apostles. The 12 apostles will be ruling from the temple in the New Jerusalem, ruling over the 12 tribes of Israel. Their names are on the twelve foundations of the temple (Revelation 21:14). !" was an important number to the Jew - it signified 'perfection'. Mathematically 12 has more factors than any other small number (1,2,3,4,6,12), and this was significant to the Jew, the number 12 occurring throughout The Bible (12 tribes, disciples, 144,000 [ie 12 x 12 in thousands] in Revelation and so on).

According to Acts 1:20-26, the disciples fulfilled the Psalm prophesy about needing to find another person to take Judas' place. It then says the disciples prayed to God about the decision after selecting two men who had been with them since the beginning of Jesus' ministry on Earth. They cast lots to make the decision, which was the equivalent of rolling dice or drawing straws, and Matthias was the one chosen. To a believer in the Bible, Matthias was chosen to be the 12th disciple because that is what God's will was. This was in accordance with a fulfillment of the Scriptures, which Peter quoted in v. 20 from Psalms 69:25 & 109:8 for replacing Judas' position. As for Biblical appropriateness of casting a lot, consider Proverbs 16:33: "The lot is cast into the lap; but the whole disposing thereof is of the LORD."

The Bible does indicate why Matthias was chosen over Barnabas - only Matthias & Joseph Justus (Barsabas) seem to be qualified for the position. Barnabas, a native of Cyprus, while being a godly Early Church believer, did not meet the criteria that Peter explained in Acts 1:21, 22. Matthias was shown to be God's choice, there being no Biblical reason to question it.

Incidentally, both Barnabas and Titus are called apostoloi (apostles) in the Greek text, which means a sent one, but they are not numbered with the original 12. Even Paul called himself "as one born out of due time. For I am least of the apostles, that I am not meet to be called an apostle, because I persecuted the church of God (before he became a Christian)." 1 Corinthians 15:8,9.