What does the Bible say about true Christian fellowship?

In his letters, the Apostle John emphasizes that true Christian fellowship is established on the foundation of truth. This means that believers must agree on key doctrines about the person and work of Christ. Fellowship is not simply about agreeing to disagree; it requires a shared understanding of who Jesus is—God manifest in the flesh, who fulfills the law perfectly on our behalf. Furthermore, Christian love flows from this truth. John makes it clear that love and fellowship can only genuinely exist when they are rooted in the doctrinal truths of the Gospel, rather than personal preferences or opinions.