I could be mistaken, but I think it is because the idea is that all three (Father, Son, Holy Spirit) are all aspects of the one being, rather than being three separate entities. Because God is beyond our comprehension, this idea often doesn't make sense to us, but that's kinda how it is supposed to be anyway. I could be wrong, being an atheist myself, so anyone feel free to correct me.

Because the Trinity - Father, Son and Holy Spirit - are three persons, or entities, in one Almighty Being. This question is answered more in detail by the Apostle's Creed which states precisely... I believe in one God, the Father, the Almighty, maker of Heaven and Earth, of all that is seen and unseen. I believe in one Lord, Jesus Christ, only Son of God,eternally begotten of the Father; God from God, Light from Light, True God from True God. Begotten, not made, One in being with the Father. Through Him all things were made. For us men and for our salvation He came down from Heaven. By the power of the Holy Spirit he was born of the Virgin Mary and became man. For our sake, He was crucified under Pontius Pilat. He suffered, died and was buried. On the third day he rose again, in fulfillment of the scriptures. He ascended into Heaven and is seated at the right hand of the Father. He will come again in Glory to judge the living and the dead, and His Kingdom will have no end. I believe in the Holy Spirit, the Lord, the Giver of Life, who proceeds from the Father and the Son. With the Father and the Son He is worshipped and glorified. He has spoken through the prophets. I believe in one Holy Catholic and Apostalic Church, I believe in the communion of saints, the forgiveness of sins, resurrection of the spirit and the life in the world to come. Amen.

Because God has revealed himself in the Trinity (which just means three in one). God the Father, God the Spirit, and God the Son. Three distinct persons, in one God. The Trinity is a very hard concept to explain, primarily because it is God, and there is nothing else like God. I will try to help you understand with an illustration, realizing that since God is unique it will fall short somewhat. An egg has the egg shell, the egg white, and the egg yolk. The egg has three distinct parts to one egg. The differece, however, is that, unlike the egg parts, the spirit of God cannot be divided (Jesus revealed himself in the flesh, was always in unison with the Father in Spirit). In the Creation account (Genesis 1:26 "Let US make man in OUR image..."), God talks to himself in the plural, revealing the three persons of the one tri-une God right off the bat. Then Jesus himself tells us of the unity of God in John 14:10 "Don't you believe that I am in the Father, and that the Father is in me? The words I say to you are not just my own. Rather, it is the Father, living in me, who is doing his work."

I think one must also understand, that The doctrine of the Godhead, and the formula you baptize under, really dont have much to do with each other. The formula of baptism using the titles the father son and holy ghost, as compared to other forms (ie in the name of Jesus only, The names Jehovah, Jesus, and the HG), is solely based on Matt 28:19. You will see other references that give a formula of baptising in the name of Jesus, as opposed to the titles, such as Acts 2:38. I ultimately feel like many people use the doctrine of the trinity to validate their formula of baptism, when they really have nothing to do with eachother.

I would only like ot step in to clarify one thing. The category is "Jehovah's Witnesses". The asker uses the word "we" in his question which could make it appear as though he is one of Jehovah's Witnesses. If one makes the assumption that he is, one could also easily make the mistaken assuption that all the answers to his question are also from Jehovah's Witnesses. This is not the case. First, the asker is NOT one of Jehovah's Witnesses. Second, all answers reffering to the trinity as the reason for the way that baptisms are performed, are also NOT from Jehovah's Witnesses. This is a reference to Matthew 28:19 where Christ told his disciples "Go therefore and make disciples of people of all the nations, baptizing them in the name of the Father and of the Son and of the holy spirit" Vice grip believes that he is going to trap one of Jehovah's Witnesses into saying "yes, that's what we do" so that he can respond with "AHA! So you admit the Holy Spirit has a name, and therefore must be a person! This is an argument I have heard a thousand times. Jehovah's Witnesses baptize in the name of the Father (Jehovah), and of the Son (Jesus Christ), and of the Holy Spirit (WHICH HAS NO NAME). Have you ever heard the expressions "in the name of love", or "in the name of justice"? Just because you do something in the name of something does not mean that something has a name or a personality. The reasons Jehovah's Witnesses do not believe in the trinity can be found here: http://www.answerbag.com/q_view/21470

(Jesus gave Peter the keys to the kingdom). Notice Acts 2:36 Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ. Act 2:37 Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do? Act 2:38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. By Obeying Acts2:38 you get into the kingdom... That is by being baptized in his name and his name is Jesus Christ. These were the men who killed Christ and they were asking how to make it right, Peter answered repent and be baptized etc...

Acts 2:38 records the Apostle Peter’s words on the day of Pentecost, “Peter replied, ‘Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit.’” This was a strong affirmation by Peter that “there is no other name under heaven given among men by which we must be saved” (Acts 4:12). Being baptized in the name of Jesus indicates an understanding by the person being baptized that Christ is the Savior. Christian baptism is also in the name of the Father, Son, and Holy Spirit (Matthew 28:19). Being baptized in this manner simply means we are identifying ourselves with the Trinity. We belong to the Father, are saved by the Son, and indwelt by the Spirit. This is similar to how we pray in Jesus’ name (John 14:13). If we pray in the name of Jesus, we are praying with His authority and asking God the Father to act upon our prayers because we come in the name of His Son, Jesus. Being baptized in the name of the Father, Son, and Holy Spirit is being baptized in identification with them and their power over and in our lives. Jesus Himself specifically tells us to baptize “in the name of the Father and of the Son and of the Holy Spirit” (Matthew 28:19). In the Book of Acts, new believers were baptized in the name of Jesus (Acts 2:38; 8:12; 8:16; 10:48; 19:5). It is, however, essentially the same thing—Jesus, the Father and the Holy Spirit are one (John 10:30; Acts 16:7). Per Jesus’ own instructions, believers should be baptized in the name of the Father, Son, and Holy Spirit, but as the book of Acts proves, baptizing in the name of Jesus is also done. The bottom line is that the name/names in which we are baptized is not as important as the recognition that baptism identifies us with the death, burial and resurrection of Christ, our Savior. We are buried with Him and risen to walk with Him in newness of life. Recommended Resource....http://www.gotquestions.org

because we have to acknowledge and accept all 3...to be baptized in TRUTH... Jehovah is the Holy Spirit and Jesus was Jehovah... they are 1....

Because Jehovah and Jesus are one and the same Being ... adn the Father wants to be included in the baptismal ceremony

how did John baptize Jesus?

Because baptism predates trinitarianism.

I love this question!!! okay,so the first thing we should adress is his true name. Jesus is a latin transcription of his name because the translation of his aramaic name is the same latin word as fish. aramaic is Iasu. his hebrew name is Yehoshua which is a mixture of two hebrew words, yhwa= I am and Shwua=savior. of course we know god answered moses his name as I am that I am. we know Christ as the savior. Christ teaches that God is a spirit so the completion of jesus name is a spiritual meaning I am the savior! The same God,the same name. Jehova,by the way, is a transliterary error,the word Hova in hebrew means desolation. The error was made because to transliterate a word into english from a hebrew language which has no vowel system is difficult to say the least. the way it was transposed in old english looks as though jehovah is phoneticly correct, when accuality the "o" is silent,and "v" usually represents the letter "W". I hope this helps.