No one knows, and Scripture is plain about that. Jesus himself said, in Matthew 24:36: "But about that day or hour no one knows, not even the angels in heaven, nor the Son, but only the Father." He repeats the point a few verses later with the parable of the thief in the night — the Son of Man will come at an hour you do not expect.
A few things the biblical text does say:
- It will be visible and unmistakable. "Every eye will see him" (Revelation 1:7). Not a secret event the world has to be told about.
- It will be sudden. Like lightning across the sky, or a trap sprung on a sleeping traveler (Matthew 24:27, 24:42–44).
- The dead will be raised first, then the living transformed, and both will meet him (1 Thessalonians 4:16–17).
- The timeline is in the Father's hands, not ours. Acts 1:7 — "It is not for you to know the times or dates the Father has set by his own authority."
So the honest Christian answer, and the one the early church has always given, is: we cannot calculate a date, and anyone who claims to is overreaching what God has revealed. The right posture isn't prediction but readiness — Peter calls it "waiting for and hastening the coming of the day of God" (2 Peter 3:12), which is less about timing than about how we live now.
Want me to pull together the main passages on the Second Coming, or the main views (premillennial, amillennial, postmillennial) on what it leads into?