Reformed Christians are biblical and confessional.  That is, we believe that the Bible is the written Word of God, authoritative for all matters of faith and practice.  Our Reformed tradition has also, from time to time, felt compelled to profess the Faith with various confessions.  Our current Book of Confessions is made up of 11 creeds, confessions, and catechisms:

The Early Church:

• The Apostles’ Creed (ca. 2nd century A.D.)
• The Nicene Creed (A.D. 325, revised A.D. 381)

The Reformation:

• The Scots’ Confession (1560)
• The Second Helvetic (“Swiss”) Confession (1561)
• The Heidelberg Catechism (1562)
• The Westminster Confession of Faith, the Larger and Shorter Catechisms (1643-1646)

Twentieth Century:

• The Theological Declaration of Barmen (1934)
• The Confession of 1967
• A Brief Statement of Faith (1983 reunion)

Here is a sample of what our confessions say about the basics of Christianity:

Scripture:

“We believe and confess the canonical Scriptures of the holy prophets and apostles of both Testaments to be the true Word of God, and to have sufficient authority of themselves, not of men. For God himself spoke to the fathers, prophets, apostles, and still speaks to us through the Holy Scriptures. And in this Holy Scripture, the universal Church of Christ has the most complete exposition of all that pertains to a saving faith, and also to the framing of a life acceptable to God; and in this respect it is expressly commanded by God that nothing be either added to or taken from the same.” (Second Helvetic Confession, 5.001-5.002)

God:

“We confess and acknowledge one God alone, to whom alone we must cleave, whom alone we must serve, whom only we must worship, and in whom alone we put our trust. Who is eternal, infinite, immeasurable, incomprehensible, omnipotent, invisible; one in substance and yet distinct in three persons, the Father, the Son, and the Holy Ghost. By whom we confess and believe all things in heaven and earth, visible and invisible, to have been created, to be retained in their being, and to be ruled and guided by his inscrutable providence for such end as his eternal wisdom, goodness, and justice have appointed, and to the manifestation of his own glory.” (The Scots’ Confession, 3.01)

Jesus Christ:

“It pleased God, in his eternal purpose, to choose and ordain the Lord Jesus, his only begotten Son, to be the Mediator between God and man, the prophet, priest, and king; the head and Savior of his Church, the heir of all things, and judge of the world; unto whom he did, from all eternity, give a people to be his seed,  and to be by him in time redeemed, called, justified, sanctified, and glorified…This office [of Mediator] the Lord Jesus did most willingly undertake, which, that he might discharge, he was made under the law, and did perfectly fulfill it; endured most grievous torments immediately in his soul, and most painful sufferings in his body; was crucified and died, was buried, and remained under the power of death, yet saw no corruption. On the third day he arose from the dead, with the same body in which he suffered; with which also he ascended into heaven, and there sitteth at the right hand of his Father, making intercession; and shall return to judge men and angels, at the end of the world.” (The Westminster Confession of Faith, 6.043, 6.046)

The Holy Spirit:

“We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son, who with the Father and the Son is worshiped and glorified, who has spoken through the prophets.” (The Nicene Creed, 1.3)

Humanity:

Q. 4. What does the Law of God require of us?
A. Jesus Christ teaches this in a summary in Matthew 22:37–40: “You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the great and first commandment. And a second is like it, you shall love your neighbor as yourself. On these two commandments depend all the law and the prophets.”

Q. 5. Can you keep all this perfectly?
A. No, for by nature I am prone to hate God and my neighbor.

Q. 6. Did God create man evil and perverse like this?
A. No. On the contrary, God created man good and in his image, that is, in true righteousness and holiness, so that he might rightly know God his Creator, love him with his whole heart, and live with him in eternal blessedness, praising and glorifying him.

Q. 7. Where, then, does this corruption of human nature come from?
A. From the fall and disobedience of our first parents, Adam and Eve, in the Garden of Eden; whereby our human life is so poisoned that we are all conceived and born in the state

Q. 8. But are we so perverted that we are altogether unable to do good and prone to do evil?
A. Yes, unless we are born again through the Spirit of God. (The Heidelberg Catechism, 4.004-4.008)

Salvation:

“WE ARE JUSTIFIED BY FAITH ALONE. But because we receive this justification, not through any works, but through faith in the mercy of God and in Christ, we therefore teach and believe with the apostle that sinful man is justified by faith alone in Christ, not by the law or any works. For the apostle says: “We hold that a man is justified by faith apart from works of law” (Rom. 3:28). Also: “If Abraham was justified by works, he has something to boast about, but not before God. For what does the scripture say? Abraham believed God, and it was reckoned to him as righteousness. . . . And to one who does not work but believes in him who justified the ungodly, his faith is reckoned as righteousness” (Rom. 4:2 ff.; Gen. 15:6). And again: “By grace you have been saved through faith; and this is not your own doing, it is the gift of God—not because of works, lest any man should boast,” etc. (Eph. 2:8 f.). Therefore, because faith receives Christ our righteousness and attributes everything to the grace of God in Christ, on that account justification is attributed to faith, chiefly because of Christ and not therefore because it is our work. For it is the gift of God.” (The Second Helvetic Confession, 5.109)

The Church:

“As we believe in one God, Father, Son, and Holy Ghost, so we firmly believe that from the beginning there has been, now is, and to the end of the world shall be, one Kirk [Church], that is to say, one company and multitude of men chosen by God, who rightly worship and embrace him by true faith in Christ Jesus, who is the only Head of the Kirk, even as it is the body and spouse of Christ Jesus. This Kirk is catholic, that is, universal, because it contains the chosen of all ages, of all realms, nations, and tongues, be they of the Jews or be they of the Gentiles, who have communion and society with God the Father, and with his Son, Christ Jesus, through the sanctification of his Holy Spirit. It is therefore called the communion, not of profane persons, but of saints, who, as citizens of the heavenly Jerusalem, have the fruit of inestimable benefits, one God, one Lord Jesus, one faith, and one baptism. Out of this Kirk there is neither life nor eternal felicity. Therefore we utterly abhor the blasphemy of those who hold that men who live according to equity and justice shall be saved, no matter what religion they profess. For since there is neither life nor salvation without Christ Jesus; so shall none have part therein but those whom the Father has given unto his Son Christ Jesus, and those who in time come to him, avow his doctrine, and believe in him. (We include the children with the believing parents.) This Kirk is invisible, known only to God, who alone knows whom he has chosen, and includes both the chosen who are  departed, the Kirk triumphant, those who yet live and fight against sin and Satan, and those who shall live hereafter.” (The Scots’ Confession, 3.16)