Who was he, background of his faith, was not a companion of Jesus and he played a major role in Christianity faith after Jesus PBUH

Paul (also known as Saul of Tarsus) was a first-century Jew who became a leading apostle in the early Christian movement. He was not a companion of the earthly Jesus.10

According to the primary documents—the New Testament (especially the Acts of the Apostles and Paul’s own letters)—here is the information:

Background and identity

• Born around 5–10 AD in Tarsus (Cilicia, in modern-day southern Turkey) to a Jewish family from the tribe of Benjamin. His Hebrew name was Saul (Sha’ul); Paul (Paulus) was his Roman name, which he used as a Roman citizen.1
• He was circumcised on the eighth day, raised as an observant Jew (“a Hebrew of Hebrews”), and trained as a Pharisee. He studied under the respected rabbi Gamaliel in Jerusalem and was zealous for the Jewish Law.4
• Before his change of direction, he actively persecuted the early followers of Jesus (called “the Way”).

Relationship to Jesus

• Paul never met or accompanied Jesus during Jesus’ lifetime and public ministry. He was not one of the Twelve Apostles or the original disciples who followed Jesus in Galilee and Judea.16
• His encounter with Jesus came after the crucifixion, through a visionary experience of the risen Christ on the road to Damascus (described in Acts 9, 22, and 26, and referenced by Paul himself in Galatians 1 and 1 Corinthians 15). This event, dated roughly 31–36 AD, led him to believe Jesus was the Messiah and to stop persecuting Christians.10

Jew or Christian?

• Ethnically and by upbringing he was fully Jewish, and he continued to identify as a Jew/Israelite even after his experience (see Philippians 3:5–6; Romans 11:1; 2 Corinthians 11:22). Early Christianity began as a Jewish movement, so the sharp later distinction between “Jew” and “Christian” did not yet fully exist in his lifetime.5
• After Damascus he became a devoted follower of Jesus and the most important missionary to non-Jews (Gentiles). He is traditionally called the “Apostle to the Gentiles.” He argued that Gentiles could be included in God’s people through faith in Christ without first becoming full converts to Judaism (e.g., without mandatory circumcision).1

Sources

The main historical documents are:

• Paul’s own letters (especially the undisputed ones: Romans, 1–2 Corinthians, Galatians, Philippians, 1 Thessalonians, Philemon), written in the 50s AD.
• Acts of the Apostles (written later, traditionally by Luke, a companion of Paul in his later travels).

Later Christian writers (Church Fathers) and tradition add details about his missionary journeys, imprisonments, and death in Rome under Nero (around 64–67 AD), but the New Testament texts above are the earliest and most direct sources. No independent non-Christian contemporary documents give a full biography of him.

In short: Paul was a highly educated Jew who never walked with the living Jesus, but after a dramatic personal revelation of the risen Christ he became one of the most influential figures in spreading the Jesus movement beyond its original Jewish setting.