At the beginning of chapter 2, Paul picks up the subject of Philippians 1:27 again. His desire that the Philippians are standing firm in one spirit, with one mind striving side by side for the faith of the gospel,
is expressed again in Philippians 2:2: Complete my joy by being of one of the same mind.
He introduces this here with a positive appeal to the gifts the Philippians had received. He does this in a modest way with the words: So, if there is any encouragement in Christ.
With this he expresses that the gifts he mentions are really present among the Philippians.
Paul first mentions the encouragement in Christ, and then the comfort from love. Comfort in the New Testament is not a feeling of being comforted, but an (objective) fact that there is deep comfort in Christ. Thirdly, he mentions the participation in the Spirit. This can refer to two things: the Philippians’ unity with the Spirit, or their interconnectedness with each other thanks to the Spirit. In this context, the second option fits best.
The fourth gift is affection and sympathy.
1 So if there is any encouragement in Christ, any comfort from love, any participation in the Spirit, any affection and sympathy,