The doctrine you refer to is the doctrine of the Trinity - but what is your question about it?
the Trinity
God the Father, and God the Son (Jesus) are one and thus neither is considered greater. God's one Church teaches and Scriptures include that Jesus is the son of God, that is the Son of the Father Who existed from all eternity, before the world and time were created. Jesus was God before His incarnation. Jesus is the only Person who has a true God nature and true Human nature. He is fully God and fully Man. He therefore has two wills, a Divine Will and Human Will. This was revealed by the Will of God. Jesus is God, the Second Person of the Blessed Trinity, which has existed for all eternity. The Blessed Trinity is One God in Three Persons, a union and communion of three Divine Persons.
The purpose of the Apostle's Creed was to set down what is the "orthodox" or standard belief concerning the nature of God, that is, God's Trinitarian nature (God is one, yet God the Father is divine, Jesus is divine, and the Holy Spirit is divine), and what each persona of the Godhead does. (God creates, Jesus dies and rises again, and the Holy Spirit empowers belief). Baptism is a sacrament of the church and doesn't bear on the doctrines being taught in the Apostle's Creed.
According to trinitarian churches, yes. Most mainstream protestant churches, the Roman catholic church, orthodox churches, and oriental orthodox churches are trinitarinan. They may have differing understandings of the nature of the trinity, but they all agree that God is one god, yet three persons.
Those who already believe in God certainly feel that by looking at nature they understand God. Similarly, those who follow animist beliefs or Wicca believe that they understand the spirits of the world when they look at God. Others look at nature and see they beauty of nature, but do not read anything divine into the experience.
No of course not because, by the blessed trinity we mean one and the same God in three divine persons.
The Church expresses her trinitarian faith by professing a belief in the oneness of God in whom there are three Persons: Father, Son, and Holy Spirit. The three divine Persons are only one God because each of them equally possesses the fullness of the one and indivisible divine nature. They are really distinct from each other by reason of the relations which place them in correspondence to each other. The Father generates the Son; the Son is generated by the Father; the Holy Spirit proceeds from the Father and the Son.
All three religions teach that there is only one God. The nature of that God is not the same in the three religions, though.
This question has been debated for years. On the one hand, you have Jesus as divine suffering and dying, and on the other you have his own words "MY God, My God, why have you forsaken me?". Christians hold that Jesus was both fully God and fully human at the same time. Therefore, in his divine nature he suffered and died, while in his human nature he suffered the ultimate separation from God that is the inevitable result of sin. (Not that Jesus sinned, but that he bore the penalty for our sins).
There is no specific Catholic God of mildew. In Catholicism, God is seen as the creator and sustainer of all things, but there is no deity specifically associated with mildew. It is more likely that mildew is seen as a natural phenomena within the context of Catholic beliefs.
The Japanese believe nature is important, and they believe in coexsiting with it in peace, and harmony. They also believethat some things of nature, like mountains, and trees, to be holy, or divine. Like Mount Fuji for example. It's considered to be the holiest of Japan's "Three Holy Mountains".
The beauty of nature reflects God. Many people think nature reflects God because they contemplate that nature is a creation of God, therefore, nature is a reflection of God. But those who have self-realization and God-realization, they go one step further. They realize that nature doesn't reflect God, nature is God. Every atom of nature is nothing but God energy. You and me may have 30 trillion cells, but in reality, every human cell is nothing but energy, the God particle, or Divine energy, this is the truth. Even the mountains and the oceans, the rivers and the seas may appear to be nature, made up of the five elements, but each of the element of nature is nothing but God energy. This is not just spirituality, but even what science advocates.