The Tombs Were Opened
At the time of Jesus' death, a couple events listed here should have convinced a lot of people that Jesus was more than an inconvenience to the religious establishment.
Barton writes about the curtain: These significant events symbolized what Christ’s work on the cross had accomplished. The temple had three main parts—the courts, the holy place (where only the priests could enter), and the most holy place, reserved by God for himself. It was in the most holy place that the ark of the covenant rested. The room was entered only once a year, on the Day of Atonement, by the high priest as he made a sacrifice to gain forgiveness for the sins of all the nation (Leviticus 16:1–34). The curtain of the temple may have been the outer curtain hanging between the court with the altar for burnt offerings and the actual sanctuary (Exodus 26:37; 38:18), or it may have been the curtain hanging between the two areas of the sanctuary—that is, between the holy place and the most holy place (also called the Holy of Holies, see Exodus 26:31–35; Leviticus 16:2, 12–15). Most likely, the curtain that was torn was between the holy place and the most holy place. Symbolically, that curtain separated the holy God from sinful people. By tearing the curtain in two from top to bottom, God showed that Jesus had opened the way for sinful people to reach a holy God.
Barton writes about the tombs opening: In Scripture, earthquakes symbolized God’s mighty acts (see Judges 5:4; 1 Kings 19:11; Psalm 114:7–8; Isaiah 29:6; Joel 3:16; Nahum 1:5–6; Matthew 28:2; Acts 16:26; Revelation 6:12; 8:5). Tombs broke open and the bodies of many holy people who had died were raised to life. The opening of the tombs and people coming back to life revealed that by Jesus’ death, the power of death was broken. Whether this event happened at Jesus’ death or at his resurrection (for the people did not go into the city until after Jesus’ resurrection), the resurrection of Jesus and of these holy people inaugurated the new age of salvation, the beginning of the “Last Days.” (See also Ezekiel 37:1–14 and Daniel 12:2 for the Jewish expectation of a bodily resurrection.)
MacArthur writes: Matthew alone mentions this miracle. Nothing more is said about these people, which would be unlikely if they remained on earth for long. Evidently, these people were given glorified bodies; they appeared “to many” (Matthew 27:53), enough to establish the reality of the miracle; and then they no doubt ascended to glory—a kind of foretaste of 1 Thessalonians 4:16.
Matthew 27:51–52New American Standard Bible: 1995 Update
And behold, the veil of the temple was torn in two from top to bottom; and the earth shook and the rocks were split.
The tombs were opened, and many bodies of the saints who had fallen asleep were raised;