Hebrews 9:28

so Christ was offered once to bear the sins of many. To those who eagerly wait for Him He will appear a second time, apart from sin, for salvation.

Matthew 24:36-40

“But of that day and hour no one knows, not even the angels of heaven, but My Father only. But as the days of Noah were, so also will the coming of the Son of Man be. For as in the days before the flood, they were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, and did not know until the flood came and took them all away, so also will the coming of the Son of Man be. Then two men will be in the field: one will be taken and the other left.