Question: Wouldn't the seventh trumpet (Revelation 11:15) be the "last trump," and wouldn't that tell us the time of the Rapture—i.e., the mid-point of the Great Tribulation?

Question (A composite of many, many questions—too many to deal with singly—concerning the Rapture and the "last trump."): The sounding of the "last trump" very clearly calls the dead from their graves at the resurrection (1 Corinthians:15:52In 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.
See All...). Since the Rapture and the resurrection of "those who sleep in Jesus" (1 Thessalonians:4:13-18 [13] 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. [14] For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. [15] 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 prevent them which are asleep. [16] 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: [17] 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. [18] Wherefore comfort one another with these words.
See All...) occur simultaneously, the "last trump" must signal the moment of the Rapture and would seemingly be heard by all the redeemed at that moment. Wouldn't the seventh trumpet (Revelation:11:15And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
See All...) be the "last trump," and wouldn't that tell us the time of the Rapture—i.e., the mid-point of the Great Tribulation?

Response: I can't say that the seventh trumpet, sounded by the seventh angel (Rv 11:15), occurs at mid-trib, much less that this marks the resurrection and Rapture of the saints. First Thessalonians 4:16 refers to the "trump of God" but does not identify it as the trumpet sounded by the seventh angel. A number of remarkable events are described as occurring when this seventh trumpet is sounded (Rv 11:15-19), but the resurrection and Rapture are not mentioned, which seems odd if they do occur at this time—nor do they seem to fit this timing.

The first three chapters of Revelation are about events happening to the church on earth. Then suddenly a "door is opened in heaven" (Rv 4:1) and John is commanded, "Come up hither...." That is the last we hear of the church on earth. From that time forward, the scene shifts to heaven except for the Second Coming, with which the Great Tribulation and Revelation both begin: "Behold he cometh with clouds; and every eye shall see him, and they also which pierced him..." (Rv 1:7).

There are numerous reasons for a pre-trib Rapture. Check the TBC reprints for more information on this subject.