Paul, What Are You Saying?
There's a lot in this passage. I'll give you a very short summary of the context here: God promised salvation to the Jews who rejected him. This rejection opened up a door for the Gentiles (non-Jews like me and probably you) to be accepted into this promise. Now that the Gentiles have began accepting this promise from Jesus, Jews will begin to see that Gentiles are enjoying the promise that was originally meant for them and they will begin to accept Jesus as well.
The Train Set
Let me start with an oversimplified example that may help paint a picture of what's going on here. Disclaimer: this isn't a perfect example, but it's simply meant to help you more tangibly understand the idea of what's going on.
Let's say there's a little boy named John with a father who loves him deeply. For Christmas, John's father got him a train set. He knew John wanted the train set, but he also knew this would be something they could do together so that he could build a deeper relationship with John, and therefore have influence in his life. His father's only condition is that John believes in him as a father and that John would invite him to join in playing with the train set. But John won't take the deal - he wants the train, but not the father.
Meanwhile, Chris, one of John's friends, sees the interaction and the promise the father made to John. Chris doesn't have a father who wants a relationship with him, so he sees this as an amazing deal - a father AND a train set! So Chris comes up to John's father and says, "You're my good father, and I'd love for you to play with the train with me." Immediately, Chris and John's father begin playing with the train set that was originally meant for John. Once John sees how Chris has accepted his father and is enjoying what was meant to be John's gift, he becomes jealous and regretful that he didn't accept the promise originally made for him. John then tells his father, "You're my good father and I would also like you to play with the train with me." At this point both John and Chris are joined as one family and got to share in each other's promise.
What Does This Mean For Me?
For us, the Gentile, the "Chris" in the story - this means that we cannot brag about this gift because it was by the father's grace that He accepted us and brought us into the promise. He doesn't look at us as less than his children, we have become His real children - we are adopted. Could John brag about being the "original" son when he wouldn't even accept what was already his? Could Chris brag about the promise that wasn't originally his, but was given to him by grace? The Father's plan is for both Jew and Gentile - John and Chris - to be fathered and cared for. Of course, He wants His sons to have the train set, but mostly He wants them to have their good Father who will provide abundance.
It's not God's need to be accepted that causes Him to do things this way, it's our need for relationship with Him that He so kindly won't let us miss out on.
- Michele Houston