We have learned over the past several weeks that the law can only bring wrath because we are sinners and cannot be justified by the works of the law. Salvation is and can only be by grace alone through faith alone.
In this text we see an example of that faith which justifies in the life of Abraham.
If we are to be saved we must trust in God as Abraham did. If we have the same trusting faith he had, we too can have assurance of our salvation.