Why is following Christ's doctrines important for Christians?

In 3 John, John emphasizes that fellowship among believers must be grounded in the truth of Christ’s doctrine. Those who do not abide in the essential truths about Christ are not part of the true church. Believers must carefully discern whom they fellowship and support based on their adherence to the doctrine of Christ. Engaging with the correct theology ensures not just doctrinal purity but also supports the advancement of the true gospel. Failing to uphold this leads to false connections and ultimately undermines the integrity of the church’s witness. Thus, abiding in Christ's teachings is vital for spiritual health and unity.