As is the case with so much of the New Testament itself, much of the Biblical record of Achaia involves the apostle Paul, the former Pharisee who at first did everything in his power to destroy Christianity, but after being personally converted by Jesus Christ on The Road To Damascus, he became one of its greatest champions - the man who at one time was involved in martyring Christians (see Stephen) ended his ministry being himself martyred as a Christian.
"At present, however, I am going to Jerusalem with aid for the saints. For Macedonia and Achaia have been pleased to make some contribution for the poor among the saints at Jerusalem; they were pleased to do it, and indeed they are in debt to them, for if the Gentiles have come to share in their spiritual blessings, they ought also to be of service to them in material blessings." (Romans 15:25-27 RSV)
"Paul, an apostle of Christ Jesus by the will of God, and Timothy our brother. To the church of God which is at Corinth [see 1 Corinthians and 2 Corinthians], with all the saints who are in the whole of Achaia: Grace to you and peace from God our Father and the Lord Jesus Christ." (2 Corinthians 2:1-2 RSV)
"For I am already on the point of being sacrificed; the time of my departure has come. I have fought the good fight, I have finished the race, I have kept the faith. Henceforth there is laid up for me the crown of righteousness, which The Lord, the righteous Judge, will award to me on that Day [see Resurrections], and not only to me but also to all who have loved his appearing." (2 Timothy 4:6-8 RSV)
Fact Finder: Even though he was converted after Jesus Christ had been resurrected and ascended into heaven, did Paul later at some time actually see Jesus Christ?
1 Corinthians 9:1
Note: Some others did also, such as the apostle John i.e. Revelation 1:12-18