Can people become saved after the rapture? Can you tell me where to find it in the Bible?
First, let me refer to an earlier question and answer which presented a study about the prophetic future. In that study we saw that the rapture occurred at the begining of the tribulation period (1 Thess 4:16-17). That same passage also tells us the Old Testament saints will be resurrected just before the Christians are raptured.
For the Lord Himself will descend from heaven with a shout, with the voice of the archangel, and with the trumpet of God; and the dead in Christ shall rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air, and thus we shall always be with the Lord. (NASB) 1 Thess 4:16-17
At that point there are no Christians going into the tribulation. Rev. 3:10 reinforces that point with, ” . . . will keep you from the hour of testing, that hour which is about to come upon the whole world.” Are there Christians in the tribulation? The answer is yes,
And it was given to him to make war with the saints and to overcome them; and authority over every tribe and people and tongue and nation was given to him. (NASB) Revelation 13:7
Also see Revelation 7:3-4. The next question is, “How did people become Christians during the tribulation?” The answer is found in Rev. 14:9-12.
And another angel, a third one, followed them, saying with a loud voice, “If anyone worships the beast and his image, and receives a mark on his forehead or upon his hand, he also will drink of the wine of the wrath of God, which is mixed in full strength in the cup of His anger; and he will be tormented with fire and brimstone in the presence of the holy angels and in the presence of the Lamb. “And the smoke of their torment goes up forever and ever; and they have no rest day and night, those who worship the beast and his image, and whoever receives the mark of his name.” Here is the perseverance of the saints who keep the commandments of God and their faith in Jesus. (NASB) Rev. 14:9-12
Notice the last part of the passage. They are saved by faith in Jesus and showing faithfulness to Christ by avoiding the mark of the beast.
This is the way men and women have always been saved. It is by placing our WHOLE trust in the Jesus – depending on Him to forgive our sins. Praise God it does not depend on us.