Every Witness has, in his ministry, run across the person who will speak of only one thing: the Trinity, and whose capacity to speak of it is inexhaustible. Think we're tenacious? We can't hold a candle to these guys, at least not on their favorite topic.
Jehovah's Witnesses do not believe in the Trinity; that is, they don't believe that the Father, Son and Holy Spirit are all actually the same person. A mere doctrinal difference? Hardly. The really fundamentalist churches refuse Jehovah's Witnesses Christian status on that account! When Isaac Newton, a staunch believer in God, began to refute the Trinity, he risked absolute ruin of his career and even his physical freedom. Prison was a real possibility. So he learned to be discreet in his comments.
Yet the Trinity defies the power of reason God gave us. If you have three persons described in different terms, who speak with each other, who are contrasted with each other, who occupy different places at the same time, common sense dictates that they are different persons, not the same. (One of them, in fact, turns out not even to be a person) God speaks to Jesus. Jesus prays to God, for example, when being put to death. "Forgive them, Father, for they know not what they do." And we're to believe they are the same person? Has common sense absolutely died?
Does this "common sense" argument prove that the Trinity is untrue? No. Sometimes unintuitive things turn out to be true. However, it does show that the burden of proof lies, not with me to prove what reason would indicate is obvious, but with you to prove that the seemingly absurd is, in fact, the way matters really are.
And reasonable people will require solid proof. They won't accept things that, in any other context, would instantly be recognized as a metaphor, figure of speech, or personification, since any good book makes liberal use of all these devices. No. They will want solid proof, otherwise, they are simply being gullible.
Since Jesus and his Father speak with one another, occupy different places at the same time, and are said to have different abilities, will anyone not instantly recognize their "being one" as a literary device to convey their close harmony? And if, say, you run across a scripture which says they are "equal," what does that prove? Aren't there myriad situations today in which different persons are said to be "equals"? Does anyone for one second take that to mean they are physically the same person? No! People immediately realize the expression refers to equality of stature, rank, responsibility, and so forth. With regard to the Father and Son, there are hundreds of such literary expressions. You don't plow through each one individually because the same argument applies to them all: a figure of speech in any other context is not enough to override common sense.
What do you do with a person who, when you say "don't beat around the bush," insists on looking for the bush, who will not acknowledge that the "bush" is not literal, since he "reasons" that you say what you mean and mean what you say? What do you do with such a person? I wish I knew.
Jesus has the key role in fulfilling God's purpose toward His creation. "For no matter how many promises God has made, they are "Yes" in Christ." (2 Cor 1:20 NIV)
They've always worked very closely together, even before the Son came to earth. "He is the image of the invisible God, the firstborn over all creation. For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him. Col 1: 15, 16 [A good analogy. When you see your image in the mirror, you see something which looks just like you. Nobody, however, supposes that it actually is you in the mirror.]
Following Christ's death and resurrection, the closeness with his Father continues and his authority grows: "All authority in heaven and on earth has been given to me," he told his disciples upon his resurrection." (Matt 28:18)
These scriptures are more than enough to account for the many places in which the Son and Father are shown to fulfill the same role/do the same things. There is no reason to think they would override the obvious: that persons who speak with each other are actually different persons.
Of course, you can always say, and Trinity people do, that the reason you can't figure it out is that "God's ways are higher than your ways." (Isa 55:9) Well, maybe. But can't you use the God's higher ways argument to sell any bill of goods that otherwise makes no sense at all? What's wrong with Galileo's point of view? "I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use."
Galileo, of course, is the fellow who dropped two masses of different weights from the Leaning Tower of Pisa (which leaned less at the time) and took note that they landed simultaneously. Thus, he demonstrated acceleration was independent of mass. He also got into a scrap with the Church for announcing that the earth revolved around the sun, contradicting the latter's decree that just the opposite happened. But Galileo was not an anti-God heretic. Like all scientists of his time, he viewed his work as uncovering God's modus operandi, thus glorifying Him as Creator.