Question: Do Christians need to keep the Jewish feasts?
No, we don’t need to keep the Jewish feasts, nor do we want to.
That was the whole point of the Book of Hebrews, where Paul argued with the Jews who didn’t want to let go of the Levitical system or the Mosaic system that Jesus had abolished on the cross. The tearing of the veil in the temple when Jesus died symbolized the end of that system. But we do need to study and understand the feasts because every major event in God’s Plan of Salvation is encoded in the succession of the seven sanctuary feasts.