Amadeus wrote "If God has only one personage, why would he say: "trust in Me, and trust also in Me?"
Amadeus-
I can say trust me and what I'm telling you. Or trust me and my word. Now, according to your reasoning, I wouldn't disagree that God sent part of himself. And that is the big point. Part of himself and not another person/god came. But God sent part of himself. I don't disagree with your reasoning there. But to call that part another person, that is where my disagreement comes in. Scripture tells us time and time again that there is only One God. It is not right to try and divide Him.
Amadeus wrote: "Another question: Why did Jesus tell us to baptise in the name of the Father, the Son, and the Holy Spirit?"
That is a very good question. Being as though the apostles baptized them in Christ's name and not those titles make the question even more interesting. I can't tell you why. But I do know this, that He said name (singular). And not titles of. So one God has one Name.
Amadeus think about this. God is considered as the creator of all. And they also refer to Christ as the creator of all. The reason is because God spoke and it was. Through Christ (His Word) was all things created. God spoke and gave birth to a Word; the first of all creation and by Him were all things created.
A God is capable of doing things that we wouldn't be able to understand and He did. But He says that He will teach us and lead us into all truth. I am sorry that you feel that I am thinking too much like a man. For these things being said are spiritual and not physical.