Who was speaking to Jesus from the heavens at Matthew 3:17?

I believe that it is obvious - the heavenly Father. What I would like to know is what truly is the point of all your posts regarding Jesus Christ? I respect your doctrinal position that you consider Jesus Christ as just a man and not God. That's for you. For me, its different. Therefore, let us allow God to judge us in the day of His judgment. What we can do is become salt and light in this world to make it a better place for some, and for others to come to the knowledge of the Truth.

If you actually want a real answer to your question, if you want to really know why we believe this, then I will answer-I am answering as a clergyman-and this is the answer which any schooled Anglican/Catholic/Orthodox would give; Jesus was talking to the Father. If that sounds like a surprsing answer, it is because here you are kind of confusing a subject here-Trinitarian teaching does not say Jesus is the same person as the Father. That is a heresy called Modalism. However, your question is somewhat superficial, because in asking it, you are prematurely excluding and ignoring how the New Testament would takes Old Testament passages, which are speaking of Yahweh, and applies them to Jesus-(one which explicitly refers to Yahweh's creating the universe)-or something like how Jesus can refer to Himself by an Old Testament name of God "I am the First and the Last" (Revelation)-an Old Testament name of Yahweh, which is explicitly meant to refer to Him as the Primal Being. Those verses exist and that is a fact-and Trinitarians who believe them are not watering them down, not distorting them, and to say, as many JW's do of us, that we don't know the Bible, is frankly dismissive. Btw, if you are curious about what the Greek term "Only Begotten Son" means, then you may wish to look at my post on the subject-it may not mean what you think it does-but there I look at the term historically, as well as the doctrine itself.

It was his Heavenly Father in both instances. The human mind cannot explain away God's greatness, though it might try. God is not a magician, a ventriloquist or in any way a deceiver. He is Truth.