John Calvin Commentary Philippians 1:5

"for your fellowship in furtherance of the gospel from the first day until now;" — Philippians 1:5 (ASV)

For your fellowship. He now, passing over the other clause, states the ground of his joy — that they had come into the fellowship of the gospel, that is, they had become partakers of the gospel, which, as is well known, is accomplished by means of faith; for the gospel appears as nothing to us, regarding any enjoyment of it, until we have received it by faith.

At the same time, the term fellowship may be viewed as referring to the common society of the saints, as though he had said that they had been associated with all the children of God in the faith of the gospel. When he says, from the first day, he commends their promptness in having shown themselves teachable as soon as the doctrine was set before them. The phrase until now denotes their perseverance.

Now we know how rare an excellence it is to follow God immediately when He calls us, and also to persevere steadfastly to the end. For many are slow and reluctant to obey, while there are still more that fall short through fickleness and inconstancy.