Philippians 1:5

Textus Receptus:
επι τη κοινωνια υμων εις το ευαγγελιον απο πρωτης ημερας αχρι του νυν

King James:
For your fellowship in the gospel from the first day until now

Comments:
for your fellowship in the gospel: Literally, "upon" their fellowship. While he is able to give thanks through Christ for groups whose behavior does not merit it, Paul has an additional cause for thanks with the Philippians which is specific to them. Their "common" (the root from which "fellowship" is derived) holding with Paul in the gospel gives him a reason to be thankful to God.

from the first day: One of the things that may motivate Paul's thanksgiving for the Philippians is that he was there from the first day of their participation in the gospel. Acts 16:12-40.

until now: Their faithfulness in that fellowship also elicits thanks from Paul. That Christ is Lord merits thanks from any believer. But the faithfulness of God's people can also bring glory to God, in the form of thanks in this case, in other ways as in 1 Peter 2:12. This phrase also creates a parallel with "until the day of Jesus Christ" in verse 6.

Paraphrase:
I give thanks on the commonality we have in the good news of Christ from the moment you heard it until this very day.