“Worthy are you to take the scroll and to open its seals, for you were slain, and by your blood you ransomed people for God from every tribe and language and people and nation!" Rev. 5:9
“This gospel of the kingdom will be preached throughout the whole world as a testimony to all the nations, and then the end will come.” Mat. 24:14
Perhaps Jesus was even referring to the Preaching Angel, for "the end" more likely refers to the end of this age before the millennium or before the judgment. The rapture or the beginning of the tribulation are not really an end. They happen in the midst of things.