The mysterious event known as the Rapture is most clearly presented in Paul's first letter to the Thessalonians, in which he encourages the grieving Christians that, at the "great snatch," they will be reunited with those who have died in Christ before them.
But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not precede them which are asleep. For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first. Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. Wherefore comfort one another with these words. -1 Thessalonians 4:13-18
In verse 17, the English phrase "caught up" translates the Greek word Harpazo, which means "to seize upon with force" or "to snatch up."