New International Version:
Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham’s offspring—not only to those who are of the law but also to those who have the faith of Abraham. He is the father of us all.
King James Bible:
Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
As will be clear to those who have been following Paul’s discussion, most translations, including these two, reverse the whole thrust of his argument at this point. This is because they have taken the Greek word order straight into the English, hoping that would work. As a result, what they say is that we could receive the promise either through keeping the law or by faith – which totally contradicts Paul’s main argument. The important difference is that the “only” should relate to the law, ie ‘only the law’ not ‘only those who have the law.’ Then they confirm their misunderstanding by putting ‘also to those who have the faith’ when it needs to be ‘to all who have the faith.’
The Mouse Companion Version (MCV):
Therefore it is by faith, so it can be an act of grace, thus confirming the promise to all the descendants, not to those who only have the law, but to all who have the faith of Abraham, the father of us all;
The important point is that the promise is entirely of grace because otherwise it could not be guaranteed since even those under the law couldn’t keep it. Grace is gained by faith, not legalism, so no one is excluded by not being under the Mosaic law. Faith on its own is good; law on its own is worthless. Paul is not closing the door to those who have been brought up to obey the law, he’s just telling them that it can never make them right with God – what they need is real faith. And it’s not that as followers of Jesus we can break the law – we believe the word of God, allowing Jesus to fulfill the law within and through us. Abraham is our spiritual father by our faith, not by our legalisms. >ᴥ<