Both verses emphatically teach that no true fellowship can exist between camps wherein one holds to truth and the other does not. We are not left to wonder about the nature of fellowship, for the Bible amply describes it. Biblical fellowship must be established and maintained with God, and with those who are in fellowship with God. Further, the fellowship God authorizes is not optional, but obligatory. Fellowship is as much a condition of discipleship as discipleship is a condition of fellowship.
Genuine fellowship is also the outgrowth of the practice of Bible doctrine.
It manifests itself through laboring in the Gospel, suffering with the children of God and worship.