Church is a community of believers and their children, where Christ is the Head and King.
The church community is founded upon and united by the common confession that Jesus is the Christ, the Son of the living God (Matt. 16:16).
This community is not just a random gathering of believers. God takes care of His church through Christ's under-shepherds (pastors and elders along with deacons) to provide protection, oversight and discipline.
Those, who belong to this community, submit themselves to the biblical oversight of Christ's under-shepherds.
The under-shepherds are accountable to God and His word and are not free from oversight and church discipline themselves.
A succinct way for us to remember what the Bible teaches about the Church comes from Dr. Derke Bergsma, who summarized the Church as the Christ Confessing Covenant Community.
"For no one can lay a foundation other than that which is laid, which is Jesus Christ." (I Cor. 3:11)
"...You are fellow citizens with the saints and members of the household of God, built on the foundation of the apostles and prophets, Christ Jesus himself." (Eph. 2:19-20)
"Fight the good fight of the faith. Take hold of the eternal life to which you were called and about which you made the good confession in the presence of many witnesses." (I Tim. 6:12)
"Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession." (Heb. 4:14)
"Therefore God has highly exalted him and bestowed on him the name that is above every name, so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father." (Phil. 2:9-11)
"And this will be my covenant with them when I take away their sins.” (Rom 11:27)
"Our sufficiency is from God, who has made us competent to be ministers of a new covenant, not of the letter but of the Spirit. For the letter kills, but the Spirit gives life" (II Cor. 3:5-6)
"And likewise (he took) the cup after they had eaten, saying, 'This cup that is poured out for you is the new covenant in my blood.'" (Luke 22:20)
"And all who believed were together and had all things in common. And they were selling their possessions and belongings and distributing the proceeds to all, as any had need. And day by day, attending the temple together and breaking bread in their homes, they received their food with glad and generous hearts, praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved." (Acts 2:44-47)
"And let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near." (Heb. 10:24-25)