Romans 4:16

That is why it depends on faith, in order that the promise may rest on grace and be guaranteed to all his offspring--not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all  Romans 4:16

Earlier, in verse 13, Paul had spoken of the promise to Abraham and his offspring, that they would be heir of the world - ultimately referencing the eternal salvation of God's children. Paul then took a couple verses to explain that this promise is based on faith, not our efforts to obtain it.

Now, in verse 16, Paul explains further this promise of Abraham.

That is why it depends on faith

"That is why" indicates that Paul is continuing his explanation that salvation is not by works.

Important to note: God's promise of eternal life for His children depends on faith - meaning our salvation is contingent on, or cannot happen without, faith. Faith being reliance, or trustful dependance, upon Christ for our salvation - apart from works.

The promise of eternal salvation depends on our faith that Christ alone is sufficient. 

 in order that the promise may rest on grace

The reason the promise of salvation depends on faith, is so that it can rest on grace. How do these two work together? Ephesians 2:8,9 and 1 Peter 1:5 are two verses of many that reveal an amazing truth about this faith. 

For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast.  Eph 2:8,9

Here, Paul explains that faith is not a result of anything we have done, rather it is the gift of God. He repeats the fact that it has nothing to do with us attempting to somehow work it up, or gain it by asserted effort in any way. Faith is given to us as God's gift, free from works, which makes it by grace! 

who by God's power are being guarded through faith for a salvation ready to be revealed in the last time.  1 Peter 1:5

In 1 Peter 1:5, Paul again explains how this faith is given to us by God - here to protect and guard us. We are guarded "through" faith, "through" meaning the channel of an act, or how something is done. God guards us for salvation (the promise), by giving us the faith that the promise depends on! 

This is the truth that Paul has just explained in great, amazing, deep detail:

The promise of salvation is completely free (grace without works) because it depends on a faith (reliance on Christ alone for salvation) that God gives us as His gift 

He places this faith (reliance on Christ for salvation) in us by revealing to us our sinfulness in light of His perfect character, as revealed through His laws and commands - and the wrath that awaits those who die in their transgression, void of a sufficient Sacrifice. 

and be guaranteed to all his offspring

Another point that I would like to focus on here is that the promise was guaranteed to the offspring of Abraham, which we will see refers to God's children. This is such an encouragement, and I believe we should spend time meditating on this promise from our Father. We, as children of an almighty, all powerful God, who cannot lie, are guaranteed eternal salvation. 

When the days get long, and the waves of life get tough, we may wonder sometimes what God is really up to, that He would allow things to happen. We can always be encouraged that, no matter the temporary, earthly situation, we have been guaranteed an eternal life spent with our God, in His presence!  

That kind of promise, from our God, has the power to lighten the darkest hours!

--not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all

Here is where Paul again hits his proud Jewish audience with the fact that the promise to Abraham was actually God's promise to all of His children, throughout all of history, across the entire world.  Abraham, as amazing a man of faith as he was, was a vessel that God used to reveal His promise to a chosen nation. We then see the earthly shadow of this eternal promise play out through the Old Testament. 

God's promises, however, are so much bigger - they cannot be contained to an earthly shadow. God's promises are eternal, powerful, awesome, and true. They are not contingent on us, or our ability to satisfy any requirements. They are not bound to a certain nation, a certain race, or a certain church. 

This promise of salvation, given to all people, reveals God's love for His creation.

I would like to end this post with one of my favorite hymns speaking of this amazing Love:

The love of God is greater far
Than tongue or pen can ever tell;
It goes beyond the highest star,
And reaches to the lowest hell;
The guilty pair, bowed down with care,
God gave His Son to win;
His erring child He reconciled,
And pardoned from his sin.

O love of God, how rich and pure!
How measureless and strong!
It shall forevermore endure
The saints’ and angels’ song.

When years of time shall pass away,
And earthly thrones and kingdoms fall,
When men, who here refuse to pray,
On rocks and hills and mountains call,
God’s love so sure, shall still endure,
All measureless and strong;
Redeeming grace to Adam’s race—
The saints’ and angels’ song.

O love of God, how rich and pure!
How measureless and strong!
It shall forevermore endure
The saints’ and angels’ song.

Could we with ink the ocean fill,
And were the skies of parchment made,
Were every stalk on earth a quill,
And every man a scribe by trade,
To write the love of God above,
Would drain the ocean dry.
Nor could the scroll contain the whole,
Though stretched from sky to sky.

O love of God, how rich and pure!
How measureless and strong!
It shall forevermore endure
The saints’ and angels’ song.