I have often said that walking into a church doesn't make you a Christian any more than walking into a garage makes you a car. Attending church does not save us, nor does anything else we do. We are saved by grace, through faith, on account of the life, death, and resurrection of Jesus Christ alone. This truth encapsulates how we are justified before God — in other words, how we are forgiven of all sin and declared righteous in the sight of our holy and merciful Creator. It follows then that a genuine believer will not lose his or her salvation by failing to go to church.
However, the Scriptures also teach that the Christian life should be lived within the context of the family of God (Eph. 3:4-15; Acts 2) and not in isolation. Hebrews 10 clearly tells us "not to neglect the gathering of ourselves together as is the custom of some" (Heb. 10:25). Indeed, I cannot conceive of a true Christian not wanting to gather together regularly with fellow believers to worship the Lord through the sacraments and receive His Word through preaching.
Of course, our discussion presupposes the importance of being vitally connected not just to any group that claims the name of Christ, but to a healthy, well-balanced church that honors the historical and biblical Jesus. Such a church, first of all, worships God through prayer, praise, and the proclamation of the Word in the context of the essential teachings of the historic Christian faith.
These essentials include the final authority of Scripture, the Trinity, the full deity and humanity of Christ, the substitutionary atoning death of Christ, the bodily resurrection of Christ, salvation by grace alone through faith, and so forth. As well, a true church soundly administers the sacraments. Furthermore, fellowship should be an integral part of a faithful church's construct, where people come not only to give but also to use their time, talent, and treasure for the edification of the body. Finally, a healthy, well-balanced church equips and encourages people to go out and impact the world for Christ.
“Too often in our contemporary culture, theologically informed beliefs are not considered a legitimate claim to knowledge.” — Frank Beckwith