Our Christian faith is summarized by the Nicene-Constantinopolitan Creed which is shown below. It is also elaborated as shown by what follows the Creed given below.
Nicene Creed
We believe in one God, the Father, the Almighty, maker of Heaven and Earth, of all that is seen and unseen.
We believe in one Lord, Jesus Christ, the 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 Pilate; 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.
We 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.
We believe in one holy catholic and apostolic Church. We acknowledge one baptism for the forgiveness of sins. We look for the resurrection of the dead, and the life of the world to come. Amen
The elaboration of our beliefs as given by the Nicene Creed is as follows:
The sole basis of our beliefs is the Bible, God’s infallible written Word, the books of the Old and New Testaments. We believe that it was uniquely, verbally and fully inspired by the Holy Spirit and that it was written without error (inerrant) in terms of all that we need to know for our salvation through Jesus Christ ( 2 Timothy 3:15, Hebrews 4:12-13, 2 Timothy 3:16-17, 2 Peter 1:20-21), specifically:
1. There is one true God, eternally existing in three persons – Father, Son, and Holy Spirit – each of whom possesses equally all the attributes of Deity and the characteristics of personality, coequal, coeternal, consubstantial.
2. Jesus Christ is God, the living Word, who became flesh through His miraculous conception by the Holy Spirit and His virgin birth. Hence, He is perfect Deity and true humanity united in one person forever.
3. He lived a sinless life and voluntarily atoned for the sins of men by dying on the cross as their substitute, thus satisfying divine justice and accomplishing salvation for all who trust in Him alone.
4. He rose from the dead in the same body, though glorified, in which He lived and died.
5. He ascended bodily into heaven and sat down at the right hand of God the Father, where He, the only mediator between God and man, continually makes intercession for His own.
6. Man was originally created in the image of God. He sinned by disobeying God; thus, he was alienated from his Creator. That historic fall brought all mankind under divine condemnation.
7. Man’s nature is corrupted, and he is thus totally unable to please God. Every man is in need of regeneration and renewal by the Holy Spirit.
8. The salvation of man is wholly a work of God’s free grace and is not the work, in whole or in part, of human works or goodness or religious ceremony. God imputes His righteousness to those who put their faith in Christ alone for their salvation, and thereby justified them in His sight.
9. It is the privilege of all who are born again of the Spirit to be assured of their salvation from the very moment in which they trust Christ as their Savior. This assurance is not based upon any kind of human merit, but is produced by the witness of the Holy Spirit, who confirms in the believer the testimony of God in His written word.
10. The Holy Spirit has come into the world to reveal and glorify Christ and to apply the saving work of Christ to men. He convicts and draws sinners to Christ, imparts new life to them, continually indwells them from the moment of spiritual birth and seals them until the day of redemption. His fullness, power and control are appropriated in the believer’s life by faith.
11. Every believer is called to live so in the power of the indwelling Spirit that he will not fulfill the lust of the flesh but will bear fruit to the glory of God.
12. Jesus Christ is the Head of the Church, His Body, which is composed of all, living and dead, who have been joined to Him through saving faith.
13. God admonishes His people to assemble together regularly for worship, for participation in ordinances, for edification through the Scriptures and for mutual encouragement.
14. At physical death the believer enters immediately into eternal, conscious fellowship with the Lord and awaits the resurrection of his body to everlasting glory and blessing.
15. At physical death the unbeliever enters immediately into eternal, conscious separation from the Lord and awaits the resurrection of his body to everlasting judgment and condemnation.
16. Jesus Christ will come again to the earth – personally, visibly and bodily – to consummate history and the eternal plan of God.
17. The Lord Jesus Christ commanded all believers to proclaim the Gospel throughout the world and to disciple men of every nation. The fulfillment of that Great Commission requires that all worldly and personal ambitions be subordinated to a total commitment to “Him who loved us and gave Himself for us.”
“who proceeds from the Father and the Son.” This is not the original text of the Credo in question but an addition made in the 6th and finally made obligfatory in the 11th century. And this is just one example I am afraid.
You are referring to what is known as the ‘filioque’ a term which means ‘and from the Son.’ This was the center of a controversy between the Eastern Churches and Rome, ie. the Catholic Church. The Eastern Churches objected to this phrase which was added by the Roman Church many centuries after the Nicene Creed was formulated and also lead to the separation between the Eastern and Western Churches. However recognizing Christ’s divinity it is apparent that the Holy Spirit proceeds from both the First and the Second Persons of the Holy Trinity.