15 Hence there is no force in the analogy which Faustus institutes between Christ's pointing out to us what to believe and what to reject in the Old Testament, in which He Himself is predicted, and the Paraclete's doing the same to you as regards the New Testament, where there is a similar prediction of Him. There might have been some plausibility in this, had there been anything in the Old Testament which we denounced as a mistake, or as not of divine authority, or as untrue.
We do nothing of the kind; we receive everything, both what we observe as rules of conduct, and what we no longer observe, but still recognize as having been prophetical observances, once enjoined and now fulfilled. And besides, the promise of the Paraclete is found in those books, all the contents of which you do not accept; and His mission is recorded in the book which you shrink from even naming. For, as is stated above, and has been said repeatedly, there is a distinct narrative in the Acts of the Apostles of the mission of the Spirit on the day of Pentecost, and the effect produced showed who it was.
For all who first received Him spoke with tongues; and in this sign there was a promise that in all tongues, or in all nations, the Church of after times would faithfully proclaim the doctrine of the Spirit as well as of the Father and of the Son.
Source: Reply to Faustus the Manichaean (New Advent)