1cor15:50-58
Intro
1cor15:52 could be the rapture or it could be the appearance of the son of man in the sky.
This is when the believers receive their immortal body (1 Corinthians 15:52) and it could be when the dry bones happen. Saved believers have already received the promise of eternal life but I think that at the sign of the son of man they receive their immortal body (Zech 12:8,10).
Scripture
(I Corinthians 15:50-58 [KJV])
[50] Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
[51] Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
[52] In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
[53] For this corruptible must put on incorruption, and this mortal must put on immortality.
[54] So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory.
[55] O death, where is thy sting? O grave, where is thy victory?
[56] The sting of death is sin; and the strength of sin is the law.
[57] But thanks be to God, which giveth us the victory through our Lord Jesus Christ.
[58] Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord.