There was nothing vague about God to Abraham. His relationship with God was of such intimacy that he thoroughly understood His character and purpose. He knew that he could trust God to act and react within clear parameters. Abraham added up what he knew about God and about His promise that Isaac was the promised seed, reached a conclusion, and acted. He knew God would have either to resurrect Isaac or to provide a substitute. He chose to trust the One he knew has the power and is faithful.
What if, like most Americans, Abraham had just guessed, based upon vague remembrances of a Sunday school class, movies, fiction works, and paranormal inspirations? We can assume that he would have worshipped the idols of his father Terah. A right concept of God is a Christian necessity because a wrong notion of Him is the very foundation, the starting point, for idolatry. In brief, the essence of idolatry is the entertainment of thoughts about God that are unworthy of Him.
God makes this clear at Mount Sinai after making the covenant with Israel and giving them His law. In Exodus 32, Aaron, confronted by the sinful pressure of his peers, became carried away and made a stupid Golden Calf to rescue them from their perceived dilemma. Aaron and the Israelites revealed that their false concepts of God remained. God had the idol immediately destroyed. Israel sinned in attempting to determine the nature of God based on their own reasoning, and many died in a punishing demonstration of the true God's wrath at this egregious sin.
The Israelites of today are still at it; modern Israelites are fantasizing about God. The idolater simply imagines a conception of God and then acts as though his conceptions are true. He is deceived and certainly does not know the true God as Abraham did.
God seeks out those with whom He desires to make the covenant. At that time, all they understand about Him is in broad terms. They are then to seek Him out to know Him more precisely. Those who make the New Covenant with God are required to seek out intimate details regarding His nature, purpose, and character.
John W. Ritenbaugh
Seeking God (Part One): Our Biggest Problem
Notice our example of faith, Abraham, the "Father of the Faithful." As Abraham had the knife raised to sacrifice his son, the only evidence he had was the words of God. Abraham could believe God—take Him at His word—or believe all the evidence he could see that the son of promise would die before God fulfilled His promises. Abraham could not "see" what God was going to do. As far as Abraham was concerned, Isaac was dead. The only "evidence" he had that it all would work out was God's words—the promises God made to him.
God also needed evidence. God did not know for sure what was in Abraham's heart (Genesis 22:12) until Abraham made the decision to trust God rather than all the physical evidence around him. The patriarch's actions proved he would walk by faith and not by sight.
To walk is an action. So even the phrase "walk by faith" demonstrates that living faith requires action. Our evidence is God's words. God's evidence is our actions.
We are in the same boat as Abraham. So says Galatians 3:6: "You have exactly the same experience as Abraham. Abraham took God at his word, and that act of faith was accepted as putting him into a right relationship with God" (William Barclay). Just as Abraham had to choose between believing God and believing the circumstances he could see, God also has to put us into exactly the same position. He must find out what is the true intent of our hearts—the depth of our faith. God needs to "know" that we will trust Him, no matter what, before He commits to a permanent, eternal relationship with us.
Faith—What Is It?