"But the Lord SAID unto him, (Ananias), GO THY WAY: FOR HE (Paul) IS A CHOSEN VESSEL UNTO ME, TO BEAR MY NAME BEFORE THE GENTILES, AND KINGS, AND THE CHILDREN OF ISRAEL: FOR I WILL SHEW HIM (Paul) HOW GREAT THINGS HE MUST SUFFER FOR MY NAME'S SAKE." Acts 9: 15,16.
These are Jesus Christ's own words concerning Paul. ( They are probably in red in your BIble). I'm sure He is not concerned about your opinion of Paul as much as He is concerned about the message He gave Paul to give you.
That is correct - it is red. However, the question has been asked before this whether Paul is a real Apostle (as in the 12), or a named person of the Lord such as in the OT?
The Church is clear in its teaching - that Paul is as great an Apostle as Peter. However, the Bible does not quite grant that - Paul does not have the same qualifications as those who spent 3 years with Jesus, and if you read his epistles, he has a great sense of inferiority because of that.
That establishes Paul’s apostleship, being selected by Jesus Himself.