Being a part of the kingdom of God means there is a task at hand. Each of us, once receiving the Spirit, is also given gifts—talents to help us further the goals of the Kingdom (1 Corinthians 12:27-31). What we have to realize though is that we aren’t given these gifts so that we can work alone. Community is desperately important for two reasons.
First, we are in community to build and be built back up. When we gather together, scripture actually tells us that we should be in the process of building one another up according to each other’s needs (Ephesians 4:29). Let’s consider it this way—if we are constantly pouring out what we have for the Kingdom but are never refilled, eventually we will be running on empty. We are filled by the Word of God and the community of believers. If you are regularly pouring out but not grafted into a community (small group, Sunday school class, Bible study, Encourager's group, etc.) you are setting yourself up to be emptied and burned out.
Second, we are in community because we do not all have the exact same gifts and purposes. God tells us that we are all one body made up of many parts (1 Corinthians 12:12-14). In the same way that our physical bodies cannot function as well without all of our parts, then the church—Christ’s Bride—will have similar dysfunction. We are not created to do it on our own. It is wrong even for us to tell other parts of the body that we don’t need them to achieve the task at hand (1 Corinthians 12:21-26). Simply put—community, unity, is essential for the body of Christ.