Sound doctrine is actually found most easily in APOSTOLIC CREEDS such as the Nicene Creed, the Apostles Creed. Creeds were written to summarize the essentials of Christian faith. The Creed certainly expresses beliefs found in the NT. But often those beliefs in the NT are not clearly expressed inasmuch as they were not generally written to teach specific theology, and were written over a long period of time by different authors addressing different situations. Nothing in a Creed contradicts the bible, rather it elucidates what is found in the bible, connecting thoughts and placing articles of faith in a concise summary.
The Nicene Creed expresses so well the bare minimum of belief which comprises a Christian:
1. The Trinity
2. Jesus as the Son of God begotten by the Father
3. Jesus born of Mary
4. Jesus rose from the dead
5. Jesus will come again to judge the living and the dead
6.God's kingdom will have no end
7. The Holy Spirit proceeds from the Father and the Son, is God
8. Belief in the Resurrection of the dead
One has to wonder what "agreement" is being done and who with before anyone starts defending the creeds. The good fight is keeping the faith.. not defending the creeds.
As much as I have been made familiar by the Apostles Creed, it is an agreement with the RCC and such the wordings in it are circumspect for anyone in the world to be reading it as Protestant agreeing with the one Catholic church.
The Nicene creed has the Holy Spirit as the Giver of Life and to be worshipped with the Father and the Son whereas scriptures says Jesus is the bread of life that giveth life to the world and the Holy Spirit does not seek to be worshipped in the place of worship as He is in us to lead us to honour the Son by testifying of the Son to glorify the Son, and thereby the Father as well.
So the creeds are deceptive... as one believer has stated that a cult is someone that gives nine truths and slips in one lie, we can see many lies in the RCC that the Protestant churches should know better than to be identified with the RCC of its creeds done in ecumenical format.
2 Corinthians 6:14Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
15And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?
16And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.
17Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you. 18And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.