Common grace and salvation grace

Common grace:
The ability to believe in universally distributed evenly to all human being
We are being created with the ability to believe.
God had created in human the ability to respond to God and he is the only creation with this ability.

Man is what he reacts before God.
19Because that which may be known of God is manifest in them; for God hath shewed it unto them.

20For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: Romans 1

Salvation Grace(Faith)
Jesus is the creator and accomplisher of faith.
This kind of faith comes from reading the words of God and prompting of the Holy Spirit.
"For God so loved the world that he gave his only begotten Son, that whosoever believeth on him should not perish, but have eternal life. John: 3:16

The mankind can be divided into two categories:
In the Adam and in Jesus Christ