A church is an assembly of believers in whom Christ dwells, under the discipline of the Word of God, organized for evangelism, eduction, fellowship and worship, administering the ordinances and reflecting the spiritual gifts.*
Contrary to modern usage, a church is not a physical building or location. A church (according to the Scriptures) is an organized group of believers who have submitted to His Lordship and the instruction of His Word.
Some in the church will not be saved - will not have received Christ and are identified with Him in His death, burial, and resurrection. However, we are not able to judge that - only God and the person will know for certain. A church needs to accept all upon their profession of faith in Christ. A church is distinct from all other organizations because it has CHrist at it's center, and He is in their midst. without Him, it is no longer a New Testament Church.
A church seeks to study and be developed under the teaching of the Word of God. Preaching that is blessed by God is built upon His Word, and maintains Christ at the center. It is not based on stories, humor, or personal events. Preaching that God blesses is about CHrist - all about Christ.
The church is organized together for Evangelism, education, worship and fellowship. It is not a "back-slapping" community group that comes together to make each other feel good. It is organized to reach and develop those who have not believed and accepted Christ. Then, the church is responsible for instruction and guiding those who receive Christ. Then, it works together in "fellowship" to maintain and develop those who are it's own. Finally, it is the place where those who believe can bring their individual worship of God into a corporate body of worshippers.
Finally, the ordinances - baptism and communion - were given to the church to celebrate together. Baptism is symbolic of the believer's death, burial and resurrection with Christ. It is to be celebrated in the corporate body because one's individual identification with Christ and the cross also is their identification with the Body of Christ here on earth. The Lord's Table is a time of edification, fellowship, and personal introspection.
The gifts of the Spirit are for the empowering of the church to fulfill it's mission here on earth. The gifts are not for the individual's benefit, but for the continued work of the church. God gifts individuals so that the Body on earth can achieve what He has called it to do. When we focus on the gifts instead of the giver, when we focus on what the gift is like instead of what it should be used for, we then make the gifts of the Spirit idols (much like the Bronze Snake of Moses) and not what they are given for.
A New Testament church is an organized body of believers who are under Christ and His Word, organized to evangelize, educate, fellowship and worship together. This is accomplished by the proper use of the ordinances and gifts of the Spirit.
Today, as you look forward to this weekends gathering in your respective churches, consider how that you can be instrumental in maintaining your church in the call of the Great Commission of Christ.
* Towns, Elmer L. (2009) What's Right with the Church: A manifesto of Hope. Regal/Ventura CA. p214