The true offspring of Abraham is the children of promise, chosen freely by God and not based on human effort or desire. Because of this, God’s righteousness can only be obtained by faith alone in Christ alone, which the Gentiles did but the Israelites did not. The Israelites sought to establish their own righteousness, and therefore did not gain God’s righteousness through Christ. That is why Christ is a stumbling block to them, without realizing that Christ is the culmination of the law.
This Gospel message of Christ is actually near and available to everyone, Jews and Gentiles alike. All one has to do to obtain the righteousness of God (i.e. salvation) is to believe that Jesus is Lord.
This message is meant to be proclaimed, and the Israelites themselves have heard this message, but yet they rejected it. They thought they knew God through all the practices and rituals that they have heard, but yet rejected the one person to whom all these things pointed to.
