What had Paul been doing for a year with the churches in Greece regarding the collection?
Paul had spent a whole year encouraging the churches in Greece to prepare their collections for the saints in Jerusalem. He wanted the offerings ready for pickup and transport to Jerusalem, and completed before he arrived, so no one would give merely because of his presence.
Les explains that for the last year Paul had been encouraging these churches in Greece to get their offerings ready for the day when someone would come along and pick them up and transport that amount of wealth to Jerusalem. Paul was dealing with human nature: people say they will give, but often only one actually follows through. He told them that for a whole year they had been talking about getting these collections ready for the saints in Jerusalem, but they still had not done it. So he said, now let's get busy and complete it, because he wanted it all done before he got there so that they would not give because of his presence. Les notes Paul did not want anyone to feel obligated to give just because he happened to be there personally on the scene. This was all with regard to Christian giving; Paul never names 10 percent or a tithe, only the general concept of giving.
And herein I give my advice: for this is expedient for you, who have begun before, not only to do, but also to be forward a year ago.
See the restMore Questions
What does Paul tell the Corinthians to do about the giving they had started a year earlier?
Paul advises the Corinthians that since they had a readiness to will a year ago, they should now perform and complete the doing of it out of what they already have.