Romans 4  "Reckon" - the Greek word is logizomai - to take inventory, estimate, count, impute, number, reason, suppose, think on... from the root word logos - something said, spoken, reasoning, account, cause, communication, utterance, word.  " And Abraham believed God and it was reckoned to him as righteousness."  A wage is earned, not reckoned, Paul explains.  "But to the one who does not work but believes in Him who justifies the ungodly, his faith is reckoned as righteousness." ( v5)

We cannot earn righteousness.  We can not be made innocent or just by working for it.  Abraham did not "earn" righteousness by his obedience or by his circumcision.  He was declared righteous because he believed God.  So, Paul argues, circumcision or uncircumcision, does not determine righteousness.  The only thing that God reckons as righteousness is faith.

Abraham is the model of faith that is reckoned as righteousness.   He believed God's promise that he would become of father of nations. Even when years passed and he was 100 years old and Sarah was well past child-bearing years - Abraham believed.  Even though hope was fading - he believed. In fact, Paul writes, " he did not waver in unbelief but grew strong in faith, giving glory to God, and being fully assured that what He had promised, He was able to perform."  This was what God counted and declared to be righteous. 

This is the truth for us:  " those who believe in Him who raised Jesus our Lord from the dead, He who  was delivered up because of our transgressions and was raised because of our justification." 
(v24-25)
"Therefore having been justified by faith, we have peace with God through our Lord Jesus Christ." (5:1)

God declares us righteous- innocent, just.  He does not count our sins, but He counts our faith.  When we believe His promises, not wavering, being fully assured that " what He promised He was able to perform", we are from God's grace, declared righteous.  Our faith is what is reckoned as righteousness.

Father in Heaven,  Your Word, Your declaration to us that we who believe in You, who raised Jesus our Lord from the grave, that You will reckon as righteousness that faith... Oh what marvelous Grace!
Not that we have performed perfectly, not that we do all the works of the Law, not that we are strong or wise or successful or anything... but that we believe that You are able to do what You have promised... this is what counts to You!  Glorious Lord, Mighty God.  You are worthy of all our worship and praise and thanksgiving.  Thank You.  And Jesus, we thank You that we have this great salvation through You, who died for us. It is in Your Name that we pray. Amen