This chapter focuses on salvation by faith rather than by works or deeds. Paul uses Abraham as the prime example because Abraham was credited as righteous prior to being circumcised. Physical circumcision was a sign of righteousness that came later. It was a sign of obedience and faith.
For Christians, you may think of water baptism in similar terms as the Jewish circumcision. Water baptism is a sign or symbol of the inward change, of obedience to Christ and of faith.
Righteousness means to be approved by God, or in a state or condition acceptable to God, right thinking.
Justification is the process we go through in order to be declared by God as acceptable or righteous.
So Abraham was declared righteous by God. Actually it says in vs 3 – Abraham believed God and it was credited to him as righteousness.
The word “credited” is used several times in this chapter and it has to do with accounts and numbers and denotes facts rather than suppositions. There is no gray area here, it’s black and white.
The word “account” is also used, so Paul is deliberately using words in this chapter that convey certainties and facts.
The entire chapter is to show that the focus is FAITH, not works. Paul says it over and over again. If you want to be saved, focus on FAITH. God is the same yesterday, today and tomorrow and this point has not changed. It is faith that matters, not anything we can do.
We cannot climb to heaven ourselves. We cannot fly to heaven. There is NOTHING we can DO to gain salvation, except to believe.