Charles Ellicott Commentary Acts 17:3

"opening and alleging that it behooved the Christ to suffer, and to rise again from the dead; and that this Jesus, whom, [said he,] I proclaim unto you, is the Christ." — Acts 17:3 (ASV)

Opening and alleging.—The latter word is used in the sense of bringing forward proofs, and the two words imply an argument from the prophecies of the Messiah, similar to that at Pisidian Antioch. In the intervals between the Sabbaths, the Apostle worked, as usual, for his livelihood, probably, of course, as a tent-maker (2 Thessalonians 3:8).

That Christ must needs have suffered.—Better, that the Christ, as pointing to the expected Messiah, the Anointed of the Lord, whom all Jews were expecting, but whom they were unwilling to recognize in the crucified Jesus. The argument was, therefore, to show that prophecy pointed to a suffering as well as a glorified Messiah, and that both conditions were fulfilled in Jesus.