That is an excellent question! Before we look at Matthew 27:52, let’s read 1st Corinthians 15:20 & 23, “But now Christ is risen from the dead, and HAS BECOME  THE FIRSTFRUITS of those who have fallen asleep….But each one in his own order: Christ THE FIRSTFRUITS, afterward those who are Christ’s at His coming” (NKJV). It is crystal-clear from these two verses that Jesus Christ is THE FIRSTFRUITS. Verse 22 emphasizes this truth by speaking of a definite ORDER in resurrection; Christ was the FIRST to rise from among the dead and those who are Christ’s will rise at His coming (i.e. at the Rapture of the Church).

Some may be thinking, “But others rose from the dead before Him, such as Lazarus (John 11:38-44), the daughter of Jairus (Mark 9:21-43) and the widow of Nain’s son (Luke 7:11-17). True, but their resurrection was different in that they did not receive their glorified bodies and thus they died again and will be raised again when Christ comes to rapture His saints to glory (as we saw in 1st Corinthians 15:23). The resurrection of Christ was unique, for He “rose to die no more…He rose to live in the power of an endless life…He rose with a glorified body” (William MacDonald in “Believer Bible Commentary). This is what makes Him “the firstfruits of those who have fallen asleep.”

Now let’s read Matthew 27:52-53, “And the graves were opened; and many bodies of the saints who had fallen asleep were raised; and COMING OUT OF THE GRAVE AFTER HIS RESURRECTION, they went into the holy city and appeared to many.” You had mentioned verse 52 which established the fact that there were saints who rose from among the dead after Jesus died, but in verse 53 we learn that it was AFTER Christ rose from the dead that this occurred. Scripture doesn’t tell us if they received their glorified bodies at that time; if they did, then their resurrection was a foreshadowing of the resurrection of believers at the Rapture. Yet it may very well be that they (like Lazarus and others) were raised to life only to die again at some point. Either way, Jesus Christ is still “the firstfruits of them that slept.”

In closing, we have a beautiful picture in the Old Testament of the truth we’ve been considering. In Leviticus 23:10-11 we read, “Speak to the children of Israel, and say to them: ‘When you come into the land which I give to you, and reap its harvest, then you shall bring A SHEAF OF THE FIRSTFRUITS OF YOUR HARVEST, to the priest. He shall wave the sheaf before the LORD, to be accepted on your behalf; on THE DAY AFTER THE SABBATH the priest shall wave it.” The “firstfruits” here typifies Christ who was raised on “the day after the Sabbath” (see Matthew 28:1-6). The “harvest,” which took place later, typifies the resurrection of “those who are Christ’s at His coming.” The Old Testament has often been called “God’s picture-book of New Testament truth” and this is a marvelous example of this saying.  (346.1)  (DO)