If Mohhamad will not go to the mountain, then the mountain will come to Mohammad. For and understanding of the Trinity read this. If you want to discuss or criticize the Trinity, this is it, not what you may have been told by someone who was not a Trinitarian.
Note, Jews are definitely non-Trinitarians, and if a Jewish reference work can accurately and correctly summarize the doctrine of the Trinity, it should be a piece of cake for anyone who claims to be a Christian.
Source: Webster's Revised Unabridged Dictionary (1913)
Trinity \Trin"i*ty\, n. [OE. trinitee, F. trinit['e], L. trinitas, fr. trini three each. See Trinal.]
1. (Christian Theol.) The union of three persons (the Father, the Son, and the Holy Ghost) in one Godhead, so that all the three are one God as to substance, but three persons as to individuality.
A Brief Definition of the Trinity
by James White
It is necessary here to distinguish between the terms "being" and "person." It would be a contradiction, obviously, to say that there are three beings within one being, or three persons within one person. So what is the difference? We clearly recognize the difference between being and person every day. We recognize what something is, yet we also recognize individuals within a classification. For example, we speak of the "being" of man---human being. A rock has "being"---the being of a rock, as does a cat, a dog, etc. Yet, we also know that there are personal attributes as well. That is, we recognize both "what" and "who" when we talk about a person.
The Bible tells us there are three classifications of personal beings---God, man, and angels. What is personality? The ability to have emotion, will, to express oneself. Rocks cannot speak. Cats cannot think of themselves over against others, and, say, work for the common good of "cat kind." Hence, we are saying that there is one eternal, infinite being of God, shared fully and completely by three persons, Father, Son and Spirit. One what, three who's.
NOTE: We are not saying that the Father is the Son, or the Son the Spirit, or the Spirit the Father. It is very common for people to misunderstand the doctrine as to mean that we are saying Jesus is the Father. The doctrine of the Trinity does not in any way say this!
The three Biblical doctrines that flow directly into the river that is the Trinity are as follows:
1) There is one and only one God, eternal, immutable.
2) There are three eternal Persons described in Scripture - the Father, the Son, and the Spirit. These Persons are never identified with one another - that is, they are carefully differentiated as Persons.
3) The Father, the Son, and the Spirit, are identified as being fully deity---that is, the Bible teaches the Deity of Christ and the Deity of the Holy Spirit.
One could possibly represent this as follows:
he three sides of the triangle represent the three Biblical doctrines, as labeled. When one denies any of these three teachings, the other two sides point to the result. Hence, if one denies that there are Three Persons, one is left with the two sides of Full Equality and One God, resulting in the "Oneness" teaching of the United Pentecostal Church and others. If one denies Fully Equality, one is left with Three Persons and One God, resulting in "subordinationism" as seen in Jehovah's Witnesses, the Way International, etc. (though to be perfectly accurate the Witnesses deny all three of the sides in some way---they deny Full Equality (i.e., Jesus is Michael the Archangel), Three Persons (the Holy Spirit is an impersonal, active "force" like electricity) and One God (they say Jesus is "a god"---a lesser divinity than Yahweh; hence they are in reality not monotheists but henotheists). And, if one denies One God, one is left with polytheism, the belief in many gods, as seen clearly in the Mormon Church, the most polytheistic religion I have encountered.
http://www.aomin.org/trinitydef.html
Definition of the Trinity (Triunity) of God
Trinity: Websters dictionary gives the following definition of trinity: The union of three divine persons (or hypostases), the Father, Son, and Holy Spirit, in one divinity, so that all the three are one God as to substance, but three Persons (or hypostases as to individuality). Synonyms sometimes used are triunity, trine, triality. The term trinity is formed from tri, three, and nity, unity. Triunity is a better term than trinity because it better expresses the idea of three in one. God is three in one. Hypostases is the plural of hypostasis which means the substance, the underlying reality, or essence.
Ryrie writes:
A definition of the Trinity is not easy to construct. Some are done by stating several propositions. Others err on the side either of oneness or threeness. One of the best is Warfields: There is one only and true God, but in the unity of the Godhead there are three coeternal and coequal Persons, the same in substance but distinct in subsistence.13
Person: In speaking of the Triunity, the term person is not used in same way it is in ordinary usage in which it means an identity completely distinct from other persons. Actually the word persons tends to detract from the unity of the Trinity. According to the teaching of Scripture, the three Persons are inseparable, interdependent, and eternally united in one Divine Being.
It is evident that the word person is not ideal for the purpose. Orthodox writers have struggled over this term. Some have opted for the term subsistence (the mode or quality of existence), hence, God has three substances. Most have continued to use persons because we have not been able to find a better term. The word substance speaks of Gods essential nature or being and subsistence describes His mode or quality of existence.14
Essence: In its theological usage, essence refers to the intrinsic or indispensable, permanent, and inseparable qualities that characterize or identify the being of God. The words triunity and trinity are used to refer to the fact that the Bible speaks of one God, but attributes the characteristics of God to three Persons: Father, Son, and Holy Spirit.
The doctrine of the trinity states that there is one God who is one in essence or substance, but three in personality. This does not mean three independent Gods existing as one, but three Persons who are co-equal, co-eternal, inseparable, interdependent, and eternally united in one absolute Divine Essence and Being.
http://www.bible.org/page.asp?page_id=215
The Athanasian Creed follows, taken from Schaff's work:
1. Whosoever will be saved, before all things it is necessary that he hold the catholic faith.
2. Which faith except every one do keep whole and undefiled, without doubt he shall perish everlastingly.
3. But this is the catholic faith: That we worship one God in trinity, and trinity in unity;
4. Neither confounding the persons; nor dividing the substance.
5. For there is one person of the Father: another of the Son: another of the Holy Spirit.
6. But the Godhead of the Father, and of the Son, and of the Holy Spirit is all one: the glory equal, the majesty co-eternal.
7. Such as the Father is, such is the Son, and such is the Holy Spirit.
8. The Father is uncreated: the Son is uncreated: the Holy Spirit is uncreated.
9. The Father is immeasurable: the Son is immeasurable: the Holy Spirit is immeasurable.
10. The Father is eternal: the Son eternal: the Holy Spirit eternal.
11. And yet there are not three eternals; but one eternal.
12. As also there are not three uncreated: nor three immeasurable: but one uncreated, and one immeasurable.
13. So likewise the Father is almighty: the Son almighty: and the Holy Spirit almighty.
14. And yet there are not three almighties: but one almighty.
15. So the Father is God: the Son is God: and the Holy Spirit is God.
16. And yet there are not three Gods; but one God.
17. So the Father is Lord: the Son Lord: and the Holy Spirit Lord.
18. And yet not three Lords; but one Lord.
19. For like as we are compelled by the Christian verity to acknowledge every Person by himself to be God and Lord:
20. So are we forbidden by the catholic religion to say, there are three Gods, or three Lords.
21. The Father is made of none; neither created; nor begotten.
22. The Son is of the Father alone: not made; nor created; but begotten.
23. The Holy Spirit is of the Father and the Son: not made; neither created; nor begotten; but proceeding.
24. Thus there is one father, not three Fathers: one Son, not three Sons: one Holy Spirit, not three Holy Spirits.
25. And in this Trinity none is before or after another: none is greater or less than another.
26. But the whole three Persons are co-eternal together, and co-equal.
27. So that in all things, as aforesaid, the Unity in Trinity, and the Trinity in Unity is to be worshiped.
28. He therefore that will be saved, must thus think of the Trinity.
29. Furthermore, it is necessary to everlasting salvation, that we believe also rightly in the incarnation of our Lord Jesus Christ.
30. Now the right faith is, that we believe and confess, that our Lord Jesus Christ, the Son of God, is God and Man.
31. God, of the substance of the Father, begotten before the worlds: and Man, of the substance of His mother, born in the world.
32. Perfect God: perfect Man, of a reasonable soul and human flesh subsisting.
33. Equal to the Father as touching His Godhead: inferior to the Father as touching His Manhood.
34. And although He be God and Man; yet He is not two, but one Christ.
35. One, not by conversion of the Godhead into flesh; but by assumption of the Manhood into God.
36. One altogether, not by confusion of substance; but by unity of person.
37. For as the reasonable soul and flesh is one man; so God and Man is one Christ.
38. Who suffered for our salvation: descended into Hades: rose again the third day from the dead.
39. He ascended into heaven. He sits on the right hand of God, the Father almighty:
40. From whence He shall come to judge the quick and the dead.
41. At whose coming all men must rise again with their bodies;
42. And shall give account for their own works.
43. And they that have done good shall go into life everlasting; but they that have done evil, into everlasting fire.
44. This is the catholic faith; which except a man believe truly and firmly, he cannot be saved.
http://ic.net/~erasmus/RAZ101.HTM
International Standard Bible Dictionary-1. The Term Trinity:
. . .we define what is expressed by it as the doctrine that there is one only and true God, but in the unity of the Godhead there are three coeternal and coequal Persons, the same in substance but distinct in subsistence. . . The doctrine of the Trinity lies in Scripture in solution; when it is crystallized from its solvent it does not cease to be Scriptural, but only comes into clearer view. Or, to speak without figure, the doctrine of the Trinity is given to us in Scripture, not in formulated definition, but in fragmentary allusions; when we assemble the disjecta membra into their organic unity, we are not passing from Scripture, but entering more thoroughly into the meaning of Scripture.
http://www.studylight.org/enc/isb/
Catholic Encyclopedia- I. THE DOGMA OF THE TRINITY
The Trinity is the term employed to signify the central doctrine of the Christian religion -- the truth that in the unity of the Godhead there are Three Persons, the Father, the Son, and the Holy Spirit, these Three Persons being truly distinct one from another. Thus, in the words of the Athanasian Creed: "the Father is God, the Son is God, and the Holy Spirit is God, and yet there are not three Gods but one God." In this Trinity of Persons the Son is begotten of the Father by an eternal generation, and the Holy Spirit proceeds by an eternal procession from the Father and the Son. Yet, notwithstanding this difference as to origin, the Persons are co-eternal and co-equal: all alike are uncreated and omnipotent. This, the Church teaches, is the revelation regarding God's nature which Jesus Christ, the Son of God, came upon earth to deliver to the world: and which she proposes to man as the foundation of her whole dogmatic system.
http://www.newadvent.org/cathen/15047a.htm
Jewish Encyclopedia-Trinity
The fundamental dogma of Christianity; the concept of the union in one God of Father, Son, and Holy Spirit as three infinite persons. It was the Nicene Council and even more especially the Athanasian Creed that first gave the dogma its definite formulation: "And the Catholick Faith is this: That we worship one God in Trinity, and Trinity in Unity; Neither confounding the Persons; nor dividing the Substance." Equalization of the Son with the Father marks an innovation in the Pauline theology: "Yet to us there is one God, the Father, of whom are all things, and we unto him; and one Lord, Jesus Christ, through whom are all things, and we through him" (I Cor. viii. 6, R. V.), while in another passage the Holy Ghost is added (ib. xii. 3; comp. Titus ii. 13), thus rapidly developing the concept of the Trinity (II Cor. xiii. 14). Although the Judæo-Christian sect of the Ebionites protested against this apotheosis of Jesus ("Clementine Homilies," xvi. 15), the great mass of Gentile Christians accepted it.
http://www.jewishencyclopedia.com/view.jsp?artid=338&letter=T