If salvation were by works of righteousness, you could never be saved.

First of all, you could never perfectly keep God’s law in your behavior.
Second of all, even if you could somehow perfectly keep God’s law in your behavior, you could not keep it in your heart and mind.  You may not kill someone or commit physical adultery, but you certainly get angry with people and you have lusts.
Third of all, before you were ever conceived or born sin was imputed to the entire human race by the choice of Adam and Eve to disobey God in the Garden of Eden.

You commit individual acts of sin.  You inherit a sin nature.  Sin is imputed to you.

God has therefore determined to give eternal life as a free, undeserved gift to ungodly sinners who receive it by a simple act of faith.

Romans 4:16  Therefore it is of faith that it might be according to grace, so that the promise might be sure to all the seed, not only to those who are of the law, but also to those who are of the faith of Abraham, who is the father of us all

Since eternal life is God’s “promise,” you can be “sure” of it.  It does not depend at all upon you.  You can be sure you are saved because of the authority of God’s Word.

This sure promise of God is available to “all the seed, not only to those who are of the law, but also to those who are of the faith of Abraham…”  Those who are “of the law” are Jews, the nation of Israel, who were given God’s law.  No matter that they had the law, they were saved by believing in the promise of God by grace through faith.

This promise of eternal life is available to anyone who, like Abraham, believes God.  He is therefore the “father of us all.”  He is, of course, the physical father of the Hebrews.  He is also the spiritual “father” of all – Jew and Gentile – who believe in the promise of God by grace through faith.

Paul expands on this spiritual fatherhood of Abraham in verse seventeen.

Romans 4:17  (as it is written, “I HAVE MADE YOU A FATHER OF MANY NATIONS”) in the presence of Him whom he believed – God, who gives life to the dead and calls those things which do not exist as though they did;

This is a quote from Genesis seventeen.  Built-in to the Old Testament was God’s declaration that Abraham was “father of many nations,” not just the Jews.  God’s plan to save men was never confined to the physical descendants of Abraham.  It was for all men everywhere.

What did Abraham believe?  He “believed God, Who gives life to the dead and calls those things which do not exist as though they did.”

We’ll see what this means in the next few verses.

Romans 4:18  who, contrary to hope, in hope believed, so that he became the father of many nations, according to what was spoken, “SO SHALL YOUR DESCENDANTS BE.”

God’s promise to Abraham was that his descendants would be as numerous as the stars in the heavens or as the grains of sand on the earth.    This promise was “contrary to hope” because Abraham and Sarah would be physically incapable of having even one child by the time God would fulfill it.  Still, Abraham believed God’s promise.

Romans 4:19  And not being weak in faith, he did not consider his own body, already dead (since he was about a hundred years old), and the deadness of Sarah’s womb.

When God first promised Abraham he would be the father of innumerable people he was 75 and Sarah was 65.  They were still physically capable of having children.  Abraham was because he fathered Ishmael by Hagar.

Here in verse nineteen Paul was talking about Abraham at age 100 and Sarah at 90.  Abraham considered his own “body” to be “already dead” in so far as the possibility of fathering a son.  He knew “Sarah’s womb” to be “dead” as well.

Humanly speaking, the situation was hopeless.  Nevertheless he believed God’s promise that he would father a child.

Romans 4:20  He did not waver at the promise of God through unbelief, but was strengthened in faith, giving glory to God,

William MacDonald, commenting on this verse, wrote, “As far as [Abraham] was concerned there was only one impossibility, and that was for God to lie.”

The hopelessness of his condition actually encouraged his faith!  He was “strengthened in faith, giving glory to God.”

Romans 4:21  and being fully convinced that what He had promised He was also able to perform.

Abraham had no idea how God would fulfill His promise.  He was “convinced” that whatever God had “promised” He both could and would “perform.”

Does it take great, immense faith to take God at His Word?  In one sense, it does not, because, after all, He is God!  He cannot lie and He is all-powerful.  If He promises He is going to do something, it’s a sure thing He will do it.

Romans 4:22  And therefore “IT WAS ACCOUNTED TO HIM FOR RIGHTEOUSNESS.”

“Accounted,” you remember, is a bookkeeper’s term.  It means to put something over into the ledger.  When Abraham believed God, when he took God at His Word, God put “righteousness” into Abraham’s heavenly ledger.  It was not by Abraham’s works of righteousness, for he had none and could accomplish none.  It was all a gift, given to Abraham based solely on the fact he believed God’s promise.

Romans 4:23  Now it was not written for his sake alone that it was imputed to him,
Having discussed the particulars of Abraham’s belief, Paul again reminded his readers that Abraham’s story is not just about him, or even about his physical descendants.  No, he is the father of all who believe God the way Abraham did.  We all become part of God’s spiritual family by believing God.

Romans 4:24  but also for us. It shall be imputed to us who believe in Him who raised up Jesus our Lord from the dead,

Just as God “imputed” righteousness to Abraham when he believed, He imputes righteousness “to us who believe in Him who raised up Jesus our Lord from the dead.”

Abraham believed God would give life through him when it was hopeless.  We see the strength of his belief when some years later God asked him to sacrifice Isaac.  He was about to do it when God stopped him.  Later we read of Abraham that he believed God would have to raise Isaac from the dead but, at any rate, God would certainly keep His promise to Abraham.

We can’t say how much Abraham understood about his near-sacrifice of Isaac.  Did he know that it was a picture of God the Father centuries later going through with the sacrifice of His Son, Jesus, on that same spot?

When Isaac asked his father, “Where is the lamb for the sacrifice?,” and Abraham responded, “God will provide himself the lamb,” did he know he was speaking prophetically about Jesus – the Lamb of God Who takesaway the sin of the world?

All we can say for sure is that Abraham believed the promise of God to give life to many through his son, Isaac, and that if Isaac were sacrificed, God would resurrect him to thereby accomplish it.

We believe God gave life to the dead by raising Jesus from the grave.  We believe in an accomplished fact of history.

Romans 4:25  who was delivered up because of our offenses, and was raised because of our justification.

The ancient Greek word translated delivered (paradidomi) was used of  casting people into prison or delivering them to justice. “Here it speaks of the judicial act of God the Father delivering God the Son to the justice that required the payment of the penalty for human sin.” (Wuest)

Jesus was “delivered up because of our offenses.”  This has two shades of meaning:

Jesus was “delivered up,” He was crucified, because of our offenses.  Someone needed to take our place as a substitute because, as the word “delivered” indicates, sin requires death as its penalty.
Jesus was also “delivered up” in order to put our offenses away from us.

He was “raised because of our justification” means that by His resurrection of Jesus God has declared He is satisfied that sin is atoned for and He can therefore declare believing sinners “justified.”  The fact that Jesus rose tells us the price has been paid, the work is finished, and men can be saved by believing in God’s promise.

By the way, the physical, bodily resurrection of Jesus Christ is an essential Christian doctrine.  There is no justification if Jesus is not risen.

Abraham is the illustration of what God desires to do for everyone.  He stands ready and able to impute Heaven’s perfect righteousness over into your account if you simply believe Him.  You must believe God’s testimony that Jesus died for your “offenses” and that He rose from the dead for the purpose of saving you.

One commentator, William Newell, says, “God is eager to impute righteousness.”  I like that!  In all this doctrine we must never lose sight of the heart of God.  This whole plan involving judicial satisfaction was born out of love.

Some people can believe and not be saved.  In Acts Twenty-six, King Agrippa believed and assented to the facts that confirmed that Jesus was the Savior (Acts 26:27).  But he refused to trust Jesus for His salvation.

What makes the difference between those who believe and are not saved and those who believe and are saved?

“Believe” is hard to define in a way that preserves both the richness of God’s grace and the scope of your responsibility.  It is the one thing you can do without doing anything, and it is the only thing you must do to be saved.  Theologian Charles Ryrie likes the word “trust,” saying,

…The words believe and faith sometimes seem to be watered down so that they convey little more than knowing facts.  Trust, however, implies reliance, commitment, and confidence in the object or truths that one is trusting.  An element of commitment must be present in trusting Christ for salvation, but it is commitment to Him, His promise, and His ability to give eternal life to those who believe.

Those who believe and are not saved know the facts of the Gospel and may even give assent to its truthfulness, but they are unwilling to trust the Savior for their personal salvation.  Knowledge and assent to the truth without being willing to trust cannot save you.
Those who believe and are saved trust in God’s truth.  It is the only thing you can do without doing anything, and it is the one thing you must do to be saved.