A summary of Christianity from an evangelical and Reformed perspective:
The Bible (i.e., the 66 books of the Protestant Bible) is the word of God. This form of revelation is God’s ordinary means of communication with humanity. The content of the Bible, being a form of divine communication, is to be accepted as authoritative.
The Bible reveals that God is triune. God the Father is the eternal source, from whom God the Son, and God the Spirit, eternally emanate. God the Father is invisible and unknowable in and of himself, but he reveals himself through God the Son. God the Spirit is the invisible presence and power of the Father and the Son over and above and throughout the universe.
God has a plan for the world that he has chosen to create. His plan is ultimately to reveal himself to his creatures through the establishment of the kingdom of God on earth. All things come to pass in accordance with God’s decree and in a manner most appropriate for the achieving of this plan.
God created the universe through the power of his word. Through his word, he brought form to the original formless state of the earth. Through his word, he also began the process of filling the earth with living creatures, thereby overcoming the original empty state of the earth.
God created Adam and Eve in his own image to live in the garden of Eden, to enjoy God’s provision and presence. God entrusted to them and the human race the task of extending the kingdom of God throughout the earth, but this could only be done as humanity was obedient to God’s word. Upon the completion of this task, humanity would enter into an eternal Sabbath rest, living permanently in the presence of God.
Sadly, Eve was tempted by Satan, and Adam disobeyed God by eating of the fruit of the tree of the knowledge of good and evil. This led to Adam and Eve’s expulsion from the garden of Eden. Through this disobedience, humanity lost the privilege of living in the presence of God.
Despite this rebellion, God responded graciously to humanity. God has a plan to save his people, allowing humanity ultimately to be able to return to live in his presence and to experience his blessing. God’s plan of salvation was revealed with greater clarity over time. The key stages of redemptive history in the Bible are the flood with Noah, the calling of the patriarchs (Abraham, Isaac, and Jacob), the redemption of Israel from Egypt, the Sinaitic and Deuteronomic covenants, the conquest of the promised land, the Davidic covenant, the division of the kingdom, the exile of Israel and Judah, the post-exilic restoration, and the new covenant in Christ.
From the beginning of redemptive history God has indicated that he was going to bring about the salvation of the human race and the world through a chosen seed. Over time, it was revealed that this chosen seed would be a Spirit-filled King of Israel. This King, the promised Messiah and suffering Servant of God, the divine Emmanuel, would die as an atonement for the sins of his people; and having broken the power of sin, would pour out the Holy Spirit upon all flesh, in order to bring about the eschatological return of Israel and the nations in obedience to God.
The New Testament identifies Jesus of Nazareth as being the divine Messiah who was promised in the Old Testament. Through his obedient life and death on the cross, Jesus has made full atonement for the sins of his people. Through his resurrection from the grave, and ascension to the right hand of God the Father in heaven, Jesus has inaugurated the new covenant, and opened up the way for humanity to be able to safely return into the presence of God, and to begin to experience the blessing of eternal life.
Having taken his seat on the throne of the Messiah, Jesus has received the right to possess the nations, along with the right to pour out the Holy Spirit upon those whom he has chosen to experience salvation. In order to bring about the realization of the kingdom of God through his possession of the nations, Jesus has entrusted his church with the task of proclaiming the message of his death, resurrection, and lordship. Empowered by his Spirit, his messengers proclaim this message, which is the gospel; and moved by his Spirit, the elect respond in faith to this message.
Those who respond in faith to the gospel are united to Christ and his church, and share in the benefits of membership in Christ’s body: their sins are forgiven, their persons justified, and their hearts sanctified. Led by the Spirit of God, God’s people are strengthened to walk in the way of the Lord, and to persevere until the end. The destination of this walking in the way of the Lord is experiencing the fullness of eternal life in the presence of God following the resurrection of the dead on the day of judgment.