vs. 20: "But now is Christ risen from the dead, and become the firstfruits of them that slept."
This phrase, 'first fruits' is very relevant; it refers to the first harvest of fruit that is grown with the promise of an even greater crop in the future. Just as the Bible commanded Israel to render to God their first fruits (in crops, in live stock, our first born children who were especially dedicated to the LORD) we as the church today, offer God the first fruits of our labor (working as unto the LORD and not human beings) and finances (as in tithes), our time in study of His Word, prayer, and fellowship, whatever ministry the LORD has given us, etc.
God offered up His First Born (a title for one who was pre-eminent, or rank #1), the LORD Jesus Christ on our behalf, and He has risen with a promise of even greater fruit, when all the church is likewise risen from the dead!
1 PETER 1:3-5
Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you, Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.