And he believed in the Lord, and He accounted it to him for righteousness. (Gen 15,6)
In antiquity, the concept of "justice" was attributed to a person by the environment and it meant respect, respectability, esteem as a result of how that person acted among people. Abram understood this and lived in such a way that he could be considered righteous by those around him. But to be considered righteous by God - that was something else! When God Himself transferred this positive evaluation to him, Abram must have been surprised at what made it happen: the moment he believed God to fulfill His word, His impossible word... God declared him positively accepted on that basis. Abram did not have to tear himself apart in doing good deeds, but took on a special relationship to God that he had never taken on with any of his idols before. Indeed, he had not even heard of anyone who had done so towards his deity.
If we are weaned upon the New Testament theology of salvation, we know we are saved by the Christ´s sacrifice. We accept that by faith, and so we take faith quite naturally as a means to salvation, but perhaps we have never asked ourselves why is that so? Why should our faith be the bridge?
Man has fallen out of relationship with God because of his unbelief. When Adam ate of the tree of knowledge, he consciously expressed his disbelief that the way with God was the best possible way for him. He did not trust God as a being of supreme, absolute goodness. He questioned God's purpose, God's gift to man, and God's words about what was best for him. He accepted the idea, whispered to him by the serpent, that God didn't mean well with them, and might even be playing some kind of game with them. In doing so, he questioned the very character of God.
To question is nothing else than to disbelieve. Parents who have experienced their own children doubting their good intentions or character have tasted in part what must have been going on in the heart of God when Adam sinned.
Man fell out of relationship with God because of his unbelief, and that is why he gets back into it by faith.
