Pastor Rich Lusk of Trinity Presbyterian Church, Birmingham, Alabama, points out that, narratively, the entire gospel of Mark takes place during the night. The sun sets in Mark 1:32 and there is no reference to a sunrise until 16:2, on the first day of the week when the women find an open tomb. (There’s a sunrise in the parable of the sower in 4:6.)
Between sunset and sunrise Mark refers to six evenings (1:32; 4:35; 6:47; 11:19; 14:17; 15:32; the word evening is used a seventh time in 13:35), numerically matching the six evenings of Genesis 1 (there is no “evening and morning” for Day 7). In Mark, the sun rises after the sixth evening.
Mark specifically mentions darkness in two places. After the sunset of 1:32, Jesus goes out early in the morning, “while it was still dark,” to pray alone (1:35). During the three hours of Jesus’ crucifixion, darkness falls on the whole land (15:33). Jesus carries out His mission in a darkness that deepens as His mission comes to a climax on the cross.
The darkness of Mark might be taken as a symbol of evil, while sunrise symbolizes the righteousness that dawns in the resurrection of Jesus. But in Genesis 1, darkness isn’t evil; it’s what comes first. At first darkness covers the face of the water (Genesis 1:2), the evening before God calls light into being. Every day begins in the darkening of dusk and ends with light. Darkness is protological; light is eschatological. (That, I have argued elsewhere, is how light and darkness work in the gospel of John.)
Let’s stipulate that Mark is using dark/light imagery in the same way: The sun sets at the beginning of the gospel because Jesus carries out His ministry in the first creation, the evening world before the resurrection. That darkness is not evil, but becomes evil when it tries to overcome the light. Literally: Jews want to kill Jesus because He threatens the (good) evening world of Torah; Pilate agrees to execute Jesus to preserve the old world of empire.
Darkness cannot overcome the light. The custodians of evening cannot keep the sun from rising on the first day of the week, the day after the sixth evening, the new Sabbath that has no evening.