Luke mentions two consequences of spiritual fellowship: exultant song and evangelical success. The song involved exuberant praise of God, both in their formal and informal gatherings. The more they discovered about God – his character, his blessings, his promises and his purposes, the more their hearts burst forth into song. We can easily know when we have had a time of fellowship – our hearts will be full of gratitude to God.
No doubt, the secret energy that maintained the desire for fellowship was the secret inner workings of the Holy Spirit. But this secret energy revealed itself in joy and sincerity.
There is a definite connection between fellowship and joy. After spending some time in the presence of God, the psalmist declared: ‘You have put more joy in my heart than they have when their grain and wine abound’ (Ps. 4:7). Isaiah assures us that it is possible that we can ‘with joy draw water from the wells of salvation’ (Isa. 12:3). The reason why the apostle John composed his first letter concerned the joy of his readers: ‘And we are writing these things so that our joy may be complete’ (1 John 1:4). We meet with God, become joyful, receive spiritual energy to meet with God’s people, and the cycle continues.
Sincerity is also very important in maintaining fellowship. God does not meet with a two-faced person. He hates pretence, but he responds to genuineness and faithfulness. We cannot deceive God. In order to maintain fellowship with the Lord and one another, we have to be marked by heart honesty and sincerity. The combination of joy and sincerity functions like a spiritual engine enabling us to have fellowship with God and one another. And when that happens we influence other people.
Luke reminds us that onlookers were impressed by the practical Christianity found in the Jerusalem church, by their devotion to God and by their delight in one another. And each new convert added to the joy – the joy of seeing sinners converted and the joy of having more believers in their company. Fellowship has powerful effects.