Think about this: To "fellowship in the gospel," as Paul wrote, means more than being saved by the same gospel Paul preached. It goes means to be sharing in the ministry of the gospel along with Paul. It could include praying for him and supporting him as much as we do for our pastor and our missionaries. But I believe it goes beyond the prayer closet and the offering plate!
What are you doing to "share (fellowship) in the gospel?" What effort do you make to at least pray a prayer like the one in the old chorus: "Lord, lay some soul upon my heart and love that soul through me. And may I humbly do my part to win that soul for Thee"? If you pray that prayer, God will answer! And when He does He will undoubtedly lead you to take a step to let that person hear about Jesus!
Sure, not every Christian will be so bold as to witness of the streets, but we all can witness in some way! Sometimes it's simply by letting someone know that we pray for them. That can open up opportunities to share the gospel at another time. Some Christians find it easy to invite someone to a church event such as a men's breakfast, ladies' luncheon, or neighborhood Bible study. Others will bake a cake or some cookies and share these with a co-worker or neighbor and include a tract or special booklet that will give them the gospel message.
The point is, Christian, that we participate in the gospel beyond believing it. As someone let you know about Jesus, is it too much to ask that you think of letting someone else have the same chance? Seek today to share the gospel with someone.