Can you provide evidence to support the “holy trinity” or the claim that Jesus was God? The holy trinity is referred to as a “mystery”. God does not work in mysteries but makes all things known to those who love and seek him.
Contrary to your assumption, the word of God does contain mysteries. A mystery is a truth that is hidden but intimated in the Old Testament, then later revealed in the New Testament. There are eight such mysteries in the Bible. You can read a list of them here: What are the eight mysteries revealed in the New Testament?
Your doubt in the existence of a triune God is not supported by Scripture. On the contrary, the Bible describes the triune nature of God repeatedly from the first chapter of the Bible to the last. Any consideration of the Trinity struggles to reconcile a God Who is both One and Three Persons, which is inherently contradictory to our thinking. Nevertheless, the Bible holds both positions to be true.
For example, the very first chapter of the Bible makes clear God is One spiritual entity working as Three Persons.
Gen. 1:26 Then God said, “Let Us make man in Our image, according to Our likeness; and let them rule over the fish of the sea and over the birds of the sky and over the cattle and over all the earth, and over every creeping thing that creeps on the earth.”
Gen. 1:27 God created man in His own image, in the image of God He created him; male and female He created them.
In v.26, the word “God" (elohim) and the verb “make” (asah) are plural in Hebrew, indicating a triune God at work creating. This language reflects the reality of multiple Persons acting in unison and even conversing with one another.
Yet in v.27, the verb “created” becomes singular in Hebrew indicating that a single actor carried out the creative work. How do we reconcile these? Pastor Armstrong suggests one possibility is that the transition from plural to singular in Hebrew reflects how Jesus Christ acted alone as the Creator of all things, just as Paul teaches:
Col. 1:16 For by Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities — all things have been created through Him and for Him.
And as John declares:
John 1:1 In the beginning was the Word, and the Word was with God, and the Word was God.
John 1:2 He was in the beginning with God.
John 1:3 All things came into being through Him, and apart from Him nothing came into being that has come into being.
Jesus created all things and Jesus is God and yet Jesus was “with God”. So Jesus is the Creator God Who always existed and yet Jesus is also with God.
Elsewhere, Jesus Himself declares:
John 10:30 “I and the Father are one.”
The truth of the Trinity continues throughout the Bible even to the very the end in Revelation 22:
Rev. 22:16 “I, Jesus, have sent My angel to testify to you these things for the churches. I am the root and the descendant of David, the bright morning star.”
Rev. 22:17 The Spirit and the bride say, “Come.” And let the one who hears say, “Come.” And let the one who is thirsty come; let the one who wishes take the water of life without cost.
Rev. 22:18 I testify to everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues which are written in this book;
Rev. 22:19 and if anyone takes away from the words of the book of this prophecy, God will take away his part from the tree of life and from the holy city, which are written in this book.
Notice this passage is written as Jesus Himself speaking in the first person, and Jesus refers to the Spirit of God and of God (Father) in the third person as separate from Himself. Clearly, Jesus is not the Spirit or “God” in this passage since He speaks of them separately. On the other hand we know the Spirit is also God and Jesus is also God from other passages in the Bible. Once again, the Triune nature of God is evident.
Furthermore, God is eternally existent and unchanging in His nature, therefore His identity – including His Triune nature – is part of His eternal existence. This truth precludes the assumption that the Godhead is simply three “gods" working in perfect harmony, for that denies the immutability of God. Instead, the Godhead is one coexistent, coequal, coeternal power which operates as Three Persons.
So we must be careful to resist the urge to “explain away” the oneness of God or deny the triune nature of the Godhead. Theologically speaking, we’re bound by the principles of the omnipotence and eternal immutability of God. God is all powerful without equal or challenge, and there is no other god nor source of creative power in all Creation. Therefore, the members of the Godhead do not merely work together as if One. They are One yet they remain Three.
In the end, human beings inevitably reach a limit of understanding the Trinity of God, reflecting the inability of finite minds to fully grasp the concept of an infinite, eternal God.