Any doctrinal statement is ultimately an imperfect human attempt to summarize and systematize God’s perfect revelation given to us in the Scriptures.
This being said, it's important for a church to articulate how they understand, interpret and teach this revelation. Everybody says they believe the Bible, lots of heretics, cult leaders and assorted nutjobs say they believe the Bible, so what you have to do is ask "Okay, so what do you believe the Bible teaches about this or that?" What they say they teach is their doctrine.
The following summary of the major points of the 1689 Second London Baptist Confession of Faith represents what we believe in regard to the major doctrines of the Christian faith:
1. We believe in the Trinity, which is one true and living God in three Persons: the Father, the Son and the Holy Spirit. God is invisible, personal, omnipresent, eternal, dependent on none, unchanging, truthful, trustworthy, almighty, sovereign, omniscient, righteous, holy, good, loving, merciful, long-suffering and gracious.
2. We believe that Almighty God has revealed all that is necessary to life and salvation in the sixty-six books of Holy Scripture, which are the Word of God. The Scriptures of both the Old and New Testaments, being God-breathed, are infallible and inerrant in all their parts and are, therefore, trustworthy in all that they affirm.
2a. We believe in the ongoing power and ministry of the Holy Spirit in regenerating, equipping, illuminating, leading, and teaching God’s people in harmony with the final authority and sufficiency of the Bible over all areas of faith and practice.
3. We believe that God made our first father Adam perfect, holy and upright. He was appointed representative and head of the human race, which means that his disobedience to God’s commands affected all humans since.
4. We believe that Adam fell from his original righteousness into sin and brought upon himself and all his offspring death, condemnation and slavery to sin.
5. We believe it to be utterly beyond the power of fallen man to love God, to keep His laws, to understand the Gospel, to repent of sin or trust in Christ.
6. We believe that God, before the foundation of the world, and for his own glory, elected a great host of men and women to eternal life as an act of free and sovereign grace. This election was in no way dependent upon his foresight of human faith, decision, works or merit.
7. We believe that God sent his Son into the world as the man Jesus of Nazareth, Jesus the Christ, conceived of the virgin Mary by the Holy Spirit, unchangeably sinless, both God and man, born under the Law, to live a perfect life of righteousness, on behalf of his elect people.
8. We believe that God’s Son died at Calvary as a sacrifice to satisfy the wrath of God and bring about reconciliation, redemption and atonement for his elect people. God testified to the acceptance of his Son's work by raising him from the dead.
9. We believe that God’s Son ascended to the right hand of his Father and is enthroned in glory, where he intercedes on behalf of his people and rules over all things for their sake.
10. We believe that God the Son has poured out the Holy Spirit to work alongside the preached word. The Spirit of God regenerates the elect sinner and draws him irresistibly to repentance towards God and faith in Christ the Savior.
11. We believe the elect, who are called by grace, are justified in the sight of God on account of the imputed righteousness of Jesus Christ alone. This righteousness is received by faith alone.
12. We believe that all who are regenerated, called and justified shall persevere in holiness and never finally fall away.
13. We believe that the moral law of God is summarized in the Ten Commandments and that all the Ten Commandments continue today to be the standard of righteousness which every child of God ought to love and obey.
14. We believe all believers are duty-bound to join a local church as a member whenever possible, bringing themselves under church government and discipline. We also believe that baptism and the Lord’s Supper are gospel ordinances belonging only to regenerated believers and are to be practiced in the context of such local churches.
15. We believe that the Scriptures teach that only biblically qualified men are to hold the only two offices Christ has given to the Church, that being elder and deacon.
16. We believe that the local church is under the authority of Christ alone. The communion of saints, however, requires recognition of, accountability to, and fellowship with other churches.
17. We believe that the Lord Jesus Christ shall come again to raise the dead, both righteous and unrighteous, and that the righteous shall enjoy everlasting life and the wicked shall endure everlasting punishment.
(Many thanks to the International Fellowship of Reformed Baptists for their summary of the 1689 Second London Baptist Confession of Faith, of which this is a somewhat modified form. Please see the full 1689 Confession for all the Scripture references for the doctrines.)