The Two Witnesses
John 1:7 He came as a witness to testify concerning that light, so that through him all might believe.
John the Baptist, who was Elijah who is to come, came to testify concerning the light that through him all might believe. This is what the two witnesses do during the tribulation.
John 5:39 You study the Scriptures diligently because you think that in them you have eternal life. These are the very Scriptures that testify about me,
The scriptures, the law and the prophets, testify concerning Jesus. They are the two witnesses.
Luke 9:30 Two men, Moses and Elijah, appeared in glorious splendor, talking with Jesus. 31 They spoke about his departure, which he was about to bring to fulfillment at Jerusalem.
His departure -- his crucifixion, death, burial, resurrection and ascension? Yes, all of that is spoken of in the law and prophets. How about the way of salvation? Yes. These are our two witnesses, not men. The men who deliver this are irrelevant. What is a witness, the only thing that is relevant is what they witnessed, not who they are.
Revelation 11:3 And I will appoint my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth.”
To prophesy means to speak forth, to speak for, and to speak beforehand. A press secretary is a "prophet" for the president. The witnesses are simply the press secretary for Jesus.