In these two verses Paul continues his argument started in verse 15 and applies the illustration he gave there. Accordingly, what I mean is goes back as far as verse 15. The Greek expression itself is used to further argue and explain a thought already expressed. What Paul illustrated in verse 15, using an ordinary human example, is now applied to the covenant between God and Abraham. In some languages what I mean is may be rendered as “what I am trying to say is,” “the words that I spoke add up to,” or “this is really what my words mean.”
The Greek of these two verses is rather complicated; it may be interpreted as one sentence with a number of embedded clauses. Good News Translation simplifies the Greek construction, making the verse much easier for the English reader to understand.
God made a covenant with Abraham and promised to keep it translates the Greek clause “a covenant previously ratified by God.” Good News Translation expands “ratified” into two major components: (1) God making a covenant and (2) God promising to keep it. In some languages it is necessary to specify both parties involved in a covenant or agreement, and therefore it may be necessary to supply the other party, as Good News Bible does, and to add the phrase with Abraham. The phrase promised to keep it may be expressed in some languages as direct discourse, for example, “and said, I will do what I have promised,” or “and promised, I will do it.”
Four hundred and thirty years is derived by Paul from the Hebrew text of Exodus 12.40, where it denotes the number of years the people of Israel spent in exile in Egypt. In Genesis 15.13 (which Stephen uses in Acts 7.6) the period of Israel’s sojourn in Egypt is designated as four hundred years. The Septuagint text of Exodus 12.40 designates four hundred and thirty years as the length of Israel’s stay in Canaan and exile in Egypt. The important point, however, is not whether Paul is correct in his arithmetic, or how he got his figures, but that the Law was given some four hundred years after the covenant, and during all those years before the Law God’s promise to Abraham had been in effect.
In verse 18, there is a direct contrast between Law and promise. Paul strongly asserts that if God’s blessing depended on following the Law, then it cannot depend on God’s promises. (The converse is also true: if what God gives depended on his promises, then it cannot depend on the Law.) What happened in Abraham’s case is clear: God bestowed his blessing on Abraham because he promised it.
The passive construction the Law, which was given can be changed to an active construction, with “God” indicated as the agent, for example, “God gave the laws.” Also the relative clause which was given … later can be made into an independent clause. The second sentence of verse 17 may then be translated as “God gave (or, God instituted) the laws four hundred and thirty years later, but the laws cannot do away with the covenant and cancel God’s promise.” However, the expression cancel God’s promise may be rendered as “make God’s promise as though it were nothing,” or “destroy what God has promised.”
God’s gift is literally “the inheritance,” but here Paul is obviously using it, not in a literal sense, but figuratively. To a Jew, the word “inheritance” would be a reminder of the promise of God to Israel concerning the possession of Canaan, the promised land, and of what God had done in order to fulfill that promise. Therefore, the word “inheritance” came to be used figuratively to refer to spiritual favors and blessings from God. In Paul’s thought it may refer more specifically to the content of God’s promise to Abraham, namely, the gift of a right relationship with God (verse 6).
It may be very difficult in some languages to speak of God’s gift as “depending on the Law.” The relation is more likely to be interpreted as causal, and therefore one may say “if what God gives is caused by the laws,” or “if God gives because of the laws.” However, as in a number of other similar contexts, it is not the Law itself which determines God’s gift, but obedience to the Law which is here in focus. It may therefore be necessary to say in some languages “For if what God gives comes to one because he has obeyed the Law, then it does not come because of what God has promised he would do.” Such a translation would prepare the way for the conclusion to this paragraph at the end of this verse.
The last part of verse 18 can be rendered literally “but to Abraham God gave (it) by promise” (see Revised Standard Version). The “it,” of course, refers to the “inheritance” in the first part of the verse. The Greek word for “gave” is a verbal form of the word “grace”; it emphasizes the fact that what God gives he gives freely, even if those for whom the gift is intended do not deserve it. The force of the argument is that God’s blessing was given to Abraham, not because Abraham did anything to deserve it, but by virtue of God’s promise alone. The relation of reason to result in the last sentence of verse 18 must be made more specific in some languages, for example, “but because God had promised the blessing to Abraham, that was the reason why he gave it to Abraham.”
Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on Paul’s Letter to the Galatians. (UBS Handbook Series). New York: UBS, 1976. For this and other handbooks for translators see here .