CLAIM: While Joel 2:28-32 does predict the pouring out of God’s Spirit (v.17), it also predicts, “And I will grant wonders in the sky above and signs on the earth below, blood, and fire, and vapor of smoke. 20 The sun will be turned into darkness and the moon into blood, before the great and glorious day of the Lord shall come” (v.19-20). Amillennial interpreters argue that Peter is spiritualizing this OT passage. If the apostles believed that these OT prophecies should be interpreted in a spiritualized sense, then this would give us an allegorical hermeneutic for interpreting the OT. Is this the case?
RESPONSE: Peter does not mean that the moon has turned to blood or that there are clouds of smoke. Peter is not saying that this passage is completely fulfilled (e.g. moon turning to blood, sun blotted out, etc.). Instead, he is just trying to show that it is being partially fulfilled in the pouring out of the Holy Spirit (at Pentecost). In the same way, Jonah partially fulfilled the Abrahamic covenant by bringing a blessing to the Gentiles in Nineveh. However, Jonah’s partial fulfillment would not invalidate the church’s more complete fulfillment through Christ.
Peter quotes this passage to his audience to show that there is still time to repent before that final judgment, as Joel indicated in context (Joel 2:12-27). In other words, if the part about the Holy Spirit came true, then we should get ready for the parts about judgment, as well. Carson and Beale write, “It may well be that Peter quoted these verses simply because he had to use the last verse in the passage and did not feel that he could leave anything out.”
 G.K. Beale and D.A. Carson, Commentary on the New Testament Use of the Old Testament (Grand Rapids, MI; Nottingham, UK: Baker Academic; Apollos, 2007), 535.