On the first day of the week we worship because Christ rose from the dead; the first day changes all the other days for good. Likewise, His resurrection, though only something that happened once, is just the first of many in a different way. He will not rise from the dead again, but because He did many more will after Him.
Paul told the Corinthians,
in fact Christ has been raised from the dead, the first fruits of those who have fallen asleep. For as by a man came death, by a man has come also the resurrection of the dead. For as in Adam all die, so also in Christ shall all be made alive. But each in his own order: Christ the first fruits, then at his coming those who belong to Christ. (1 Corinthians 15:20–23, ESV)
On the first day of the week we remember the first fruits. “First fruits” is one Greek word, ἀπαρχή, a word that refers to the beginning that represented more. Just as there is no need for an outline without at least two points, so a first signals us to look for a second, for a succession. Paul called Jesus the firstborn from the dead (Colossians 1:18), the firstborn among many brothers (Romans 8:29).
We are an army of new men, the offspring of His offering. Supernatural life was breathed into us. We have hope not only in this life but in the life to come. We are no people to be pitied, we are a people purchased and raised and promised the glory of an imperishable body. Jesus is the first fruits and we are part of the rest of the resurrection harvest.