By which he did not exclude himself.
Given the dozens of times that Jesus alluded to his equality with God, shouldn't there be at least one clear denial that he was God if that was the case? Except there isn't, only that which would further point to that inevitable fact that He who created all things did walk among them, that he was the first and the last, the beginning and the end, and that there is no other God.
Isaiah 41:4 KJV
(4) Who hath wrought and done it, calling the generations from the beginning? I the LORD, the first, and with the last; I am he.
Revelation 2:8 KJV
(8) And unto the angel of the church in Smyrna write; These things saith the first and the last, which was dead, and is alive;
Is Jesus the first and the last person who was dead and is alive? No, "the first and the last" is used the identification for the LORD of Hosts used not once, but three separate times in Isaiah. This title also means "and beside me there is no God."
Isaiah 44:6 KJV
(6) Thus saith the LORD the King of Israel, and his redeemer the LORD of hosts; I am the first, and I am the last; and beside me there is no God.
Jesus does not exclude himself when he says that the Father is the only true God, rather he clarifies that HE Himself is that only true God in other passages. It would be unwise to ignore the express clarification of His meaning and to substitute a personal slanted interpretation from an isolated passage.
Revelation 22:13-16 KJV
(13) I am Alpha and Omega, the beginning and the end, the first and the last.
(14) Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.
(15) For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.
(16) I Jesus have sent mine angel to testify unto you these things in the churches. I am the root and the offspring of David, and the bright and morning star.