As has been asked, what type of religious community is the OP specifically thinking about? There are several types:
- A covenant community (such as the early Pilgrims journeying to these shores of America experienced) - you had to covenant to worship in like manner as to those already in the community and to be faithful in attendance, to work, to........ etc.
- A community of set apart individuals within a church - such as the Catholic church. Monasteries, convents, etc.
- A local body of believers - a local church body. These individuals usually covenant with one another to support each other with prayer and good works and to pursue the cause of Christ.
So there are several. However, it is not essentially necessary for an individual to have a relationship with Christ his Saviour or God the Father without having benefit of community with others like minded. However, we are told that we are not to forsake the assembly of ourselves with other believers. This is to provide support for each other, to help each other grow in the Lord, to admonish each other, to uphold each other in prayer before the Throne of God.