I wonder whether God the Father, the Son (Jesus), and the Holy Spirit are actually the same?
If the answer is "yes", why we can't we have our spiritual communication only with Jesus Christ?
It's three Persons in one Divine Nature, all separate in their personhood, all equal in their divinity. An image pulled from an old catechism diagrams the relationship like this:
The legendary analogy that Saint Patrick used when educating the Irish was the shamrock: three distinct leaves in one plant. Obviously, any image we make is going to be an imperfect representation of what the Trinity is, but the essence is that the three distinct persons are united in their shared Divine nature.
This particular belief, once called Sabellianism after Sabellius, is also called Modalism. In Modalism it is expressed that Father, Son and Holy Spirit are effectively three different masks or personae of the One God.
Orthodox Christians have considered this heretical since the first century, to our knowledge, because it contradicts the scriptures (for instance, who is the 'God of Jesus Christ', and how are we to interpret the prophecies in the Psalms where God makes his anointed placed above all of his brethren? They appear to not be the same person, God and 'the Lord' or 'the Anointed' (the Christ).)
But the reason why our communion is with all of the Godhead and not just Jesus Christ (as it says in our prayers, 'and have Thee (the son) and thy Father and thy Holy Spirit dwelling and abiding in me') is because they are three persons who fully indwell each other. In our liturgy and prayers this is repeated in various ways, but the most prominent is in the liturgy itself:
'Father, Son and Holy Spirit, One in essence and undivided.'
To have communion with one of the persons without the others would effectively divide the Godhead.
Augustine defined all of the following to be true:
Here is a summary of Lecture 10, "The Doctrine of the Trinity", in the class "The History of Christian Theology" by Phillip Cary, Ph.D., which helps better to explain what "is" is. "The Christian doctrine of the Trinity is about how the one true God is Father, Son, and Holy Spririt, even though these three (each of them God) are different from one another. The crucial argument developed in the 4th century was wheter the Son or Logos, the second person of the Trinity, was as fully God as God the Father. In answering yes, the Council of Nicaea in 325 laid the foundations of the orthodox trinitarian tradition. This tradition teachs that the oneness of God consists in a single divine essense or ousia, belonging equally and fully to all three, while the threeness is not three Gods but three hypostases or persons. Because all divine attributes (such as eternity, omniscience, etc.) belong equally to each, they can only be distinguished from another by their relations of origin (for example, the Father begets the Son, not vice versa)."
If the idea that the Father, Son and Spirit are all the same Being were true, we would expect that we would never see more than One of Them at the same time. Clark Kent and Superman are the same person, and the fact that you never see them together would make you start to suspect that after awhile.
In the Scriptures, we see the Father, Son, and Spirit at the same place and the same time. A classic example of this is at the baptism of Jesus:
A good way to test ideas is to try to fit them into Scripture and see what happens. In this case, it gets pretty bizarre...
Additionally, the Great Commission specifically identifies that believers ought to be baptized in the name of the Father, Son, and Spirit. If they are all the same, why not just the name of God? (Matthew 28:18-20)
Other phrases would become nonsensical as well:
So, the Scriptures are pretty clear that the Father, Son and Spirit are distinct Persons, and the Bible starts sounding extremely weird if we assume that they are the same Being. You have God being the Father of Himself, sending Himself, referring to Himself as another Being, sitting next to Himself, and all sorts of strange things.
The doctrine of Modalism or Seballianism just doesn't fit the text.