It was from God and from themselves (Man).
God used those fishermen and other ordinary men to explain to the unbelievers around them that the signs and wonders that were taking place were not caused by drinking new wine, but by the power of the risen Christ whom those people had crucified, working through those men whom God filled with His truth and enabled them to speak the Word of God with boldness and Holy Spirit power.
If I can be more specific, God's truth and doctrine was able to flow unhindered through those men who had their entire beings purified and empowered by the Holy Ghost and all the Word that Jesus had spoken to them. They did not make stuff up, but God chose to use them to expound the Word, both the old scriptures and these new scriptures.
Are you a member of catholicforum.com Adam? In my own mind I am still trying to work out just what would draw a new Catholic, to join a Christian forum. Who knows, perhaps you will find helpful and rich blessings here, with good sound doctrine, the fellowship of warm-hearted believers in Christ, and a wonderful newfound faith in the risen Jesus Christ and God who sent Him (not faith in His mother Mary and certainly not a belief in any pope). Ye must be born again, brother!