Every Christian church, or denomination, proclaims the Trinity, three persons in one God, the Father, the Son, and the Holy Spirit (or Ghost). This universal Christian doctrine is accepted, taught, and proclaimed in all Christian churches, as best expressed in the Nicene Creed. This doctrine demonstrates a unity between the Roman Catholic, Greek Orthodox, Lutheran, Presbyterian, Episcopalian/Anglican, Methodist, Baptist, Pentecostals, non-denominational and interdenominational churches, as well as all other Christian churches and denominations.
It is extremely important to notice that Christianity does not attempt in any way to say that the Trinity means three Gods are one God. Such a statement would be a logical contradiction, and therefore completely unreasonable. Instead, a unified Christianity has insisted that the Trinity means that God, while one in essence is manifested in three Persons, the Father, the Son, and the Holy Spirit. Every Christian church or denomination you enter therefore accepts the Trinity, as well as the Nicene Creed, regardless of whatever other disagreements they might have with other churches or denominations.
The Trinity is not only a unifying doctrine among churches and denominations, it also answer deep philosophical questions. One of the great questions, debates, and issues in philosophy regards the ultimate issues of unity and diversity. All around we see diversity. What gives unity to it? Without such a unity, we are only left with a wild diversity which ultimately does not sit at all well with us on a deep level as human beings. Our spirits strives at that deep level for unity. However, on that level, we cannot accept a made-up or arbitrary unity. Our spirit/souls long for an ultimate unity to that diversity, yet such a unity that does not deny or suppress the diversity we not only see all around us, but also sense or intuit in our souls. The Trinity provides a beautiful, magnificent answer to that unity and diversity our spirit/souls strive for and needs that ultimately can not be found elsewhere and corresponds to the unity and diversity all around us.
The Trinity is primarily based on the teachings about One God based in Old Testament Israel, which goes back to Abraham, and even earlier. All monotheistic religions, whether Hebrew, Islamic, or Christian, trace their roots back to Abraham (usually affectionately referred to as Father Abraham). The Trinity reflects the New Testament emphasis that Jesus Christ, on his own, refers to himself as God, and strongly implies that the Holy Spirit is also God. However, even the Old Testament implies a Trinity by such passages in Genesis where God says he will create man in our image. Denying this very historical Christian doctrine not only raises religious issues, but philosophical as well. Usually, as a society denies the Trinity, freedom tends to be restricted. This tendency most clearly manifest itself in Islamic societies where, though much of the Old Testament and the New Testament is affirmed, we easily see a restriction of freedom because of the lack of a foundation in diversity which provides a basis for freedom. Therefore, many in the West would instantly find the restrictions of a Muslim society unbearable, even though we find a common heritage in Abraham. The teachings about the Trinity largely explains why Western Civilization has led and provided the world with a maximization of freedom without falling into chaos.
In the context of the One God, promulgated and emphasized time and again in the Old Testament, as well as repeated time and again in the New Testament, the Trinity, strongly implied in the New Testament by the references by Jesus to himself as God, as well as the Holy Spirit. The Trinity avoids the errors of asserting three Gods, as well as the error of asserting that God is only one Person to the denial of Jesus Christ or the Holy Spirit as God.