This is a direct quote from the London Baptist Confession of 1689, it about says it all concerning the trinity

Chapter 2: Of God and of the Holy Trinity

1._____The Lord our God is but one only living and true God; whose subsistence is in and of himself, infinite in being and perfection; whose essence cannot be comprehended by any but himself; a most pure spirit, invisible, without body, parts, or passions, who only hath immortality, dwelling in the light which no man can approach unto; who is immutable, immense, eternal, incomprehensible, almighty, every way infinite, most holy, most wise, most free, most absolute; working all things according to the counsel of his own immutable and most righteous will for his own glory; most loving, gracious, merciful, long-suffering, abundant in goodness and truth, forgiving iniquity, transgression, and sin; the rewarder of them that diligently seek him, and withal most just and terrible in his judgments, hating all sin, and who will by no means clear the guilty.
( 1 Corinthians 8:4, 6; Deuteronomy 6:4; Jeremiah 10:10; Isaiah 48:12; Exodus 3:14; John 4:24; 1 Timothy 1:17; Deuteronomy 4:15, 16; Malachi 3:6; 1 Kings 8:27; Jeremiah 23:23; Psalms 90:2; Genesis 17:1; Isaiah 6:3; Psalms 115:3; Isaiah 46:10; Proverbs 16:4; Romans 11:36; Exodus 34:6, 7; Hebrews 11:6; Nehemiah 9:32, 33; Psalms 5:5, 6; Exodus 34:7; Nahum 1:2, 3 )

2._____God, having all life, glory, goodness, blessedness, in and of himself, is alone in and unto himself all-sufficient, not standing in need of any creature which he hath made, nor deriving any glory from them, but only manifesting his own glory in, by, unto, and upon them; he is the alone fountain of all being, of whom, through whom, and to whom are all things, and he hath most sovereign dominion over all creatures, to do by them, for them, or upon them, whatsoever himself pleaseth; in his sight all things are open and manifest, his knowledge is infinite, infallible, and independent upon the creature, so as nothing is to him contingent or uncertain; he is most holy in all his counsels, in all his works, and in all his commands; to him is due from angels and men, whatsoever worship, service, or obedience, as creatures they owe unto the Creator, and whatever he is further pleased to require of them.
( John 5:26; Psalms 148:13; Psalms 119:68; Job 22:2, 3; Romans 11:34-36; Daniel 4:25, 34, 35; Hebrews 4:13; Ezekiel 11:5; Acts 15:18; Psalms 145:17; Revelation 5:12-14 )

3._____ In this divine and infinite Being there are three subsistences, the Father, the Word or Son, and Holy Spirit, of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided: the Father is of none, neither begotten nor proceeding; the Son is eternally begotten of the Father; the Holy Spirit proceeding from the Father and the Son; all infinite, without beginning, therefore but one God, who is not to be divided in nature and being, but distinguished by several peculiar relative properties and personal relations; which doctrine of the Trinity is the foundation of all our communion with God, and comfortable dependence on him.
( 1 John 5:7; Matthew 28:19; 2 Corinthians 13:14; Exodus 3:14; John 14:11; 1 Corinthians 8:6; John 1:14,18; John 15:26; Galatians 4:6 )

I believe in the sole authority of Scripture, but I also believe that as an expression of what the scriptures teach on a given subject, that creeds and confessions are important. A creed does not have authority only the scriptures have absolute authority.