The apostle Paul practiced what he urged the Roman saints to do in Rom 12.15, to “rejoice with those who rejoice, weep with those who weep:”
Christians are joined in the body of Christ. What happens to one affects the other. “Who is weak, and I am not weak? Who is led into sin, and I do not burn with indignation?” 2 Cor 11.29. —QBT
In English we use the figure of speech about being joined at the hip. (Is that phrase still politically correct?) It means that people are very closely connected.
Christians are intimately joined in Christ. Being sanctified in him means we are separated from the world and formed into Christ’s body. We are sanctified as a unit, as the church (see Eph 5.25-27). And as the assembled ones, we are united around the Lord.
The pain of one becomes the pain of all. One brother’s joy is shared by all. Progress is made together; setbacks reverberate throughout the congregation, and even beyond.
As a recent example, we all hurt upon hearing the recent news of a youth minister arrested for sharing pornography with minors in the youth group.
On the positive side, reading about growth and baptisms in other places excites us to know what God is doing among his people. Conversions in our own congregation, even when we are not directly involved, gives us reason to praise God for his gospel.
Because we have fellowship with the Father and with his Son Jesus Christ, we have fellowship with one another, 1 Jn 1.3, 7. May we all work to deepen the common life shared in Christ.