Question: You say that “the Lord will come as a thief in the night” (2 Pt 3:10) refers to the Rapture. If so, why does Revelation:16:15 use the same terminology (“Behold, I come as a thief...”) in relation to Armageddon?
Answer: Other scriptures (Mt 25:1-13; Lk 12:35-40, etc.)suggest that the Lord will come when the church is asleep and least expecting Him. Scripture contrasts the Rapture with the Second Coming to rescue Israel in the midst of Armageddon, which is certainly not as a thief.
Far from being caught by surprise, the Jews still alive at the end of the Great Tribulation will have no excuse for not knowing that the Lord is at the very door: “when ye shall see all these things [fulfilled], know that it [His coming] is near, even at the doors” (Mt 24:33). In fact, everyone will know He is coming in judgment. Antichrist will go out with his armies to do battle with Christ: “I saw the beast, and the kings of the earth, and their armies, gathered together to make war against him that sat on the horse...” (Rv 19:19).
Certainly Revelation:16:14 (“the battle of that great day of God Almighty”) and 16:16 (“gathered them together into...Armageddon”) both refer to the battle in Revelation 19. That seems reason enough to assume that verse 15 also refers to Armageddon. But “Behold, I come as a thief...” cannot refer to Christ’s rescue of Israel at Armageddon, which is not as a thief—verse 15 can only refer to the Rapture.
Why would Christ suddenly change the subject to the Rapture between two verses about Armageddon? He seems to be warning that those who are not taken to heaven at the Rapture will be on the wrong side at Armageddon. I can think of no other reason for this interjection, which otherwise would create a contradiction that we know cannot exist.