There can be no "versus" in this matter, as if the grace of God was somehow in opposition to the grace of Christ. This can better be grasped once a clear understanding of what the grace of God is. One Christian writer has defined it like this:
"Grace is God coming down to move people to places of well-being."
Charles Strohmer, "Explaining the Grace of God" p11 (Sovereign World,
1993)
Examples are given, such as with Noah, who "found grace in the eyes of the Lord" via the Ark (Genesis 6:8). God uses various means to effect his gracious provisions, such as by sending two angels to rush Lot and his family out of Sodom (Genesis 19:1-29). Strohmer notes this important point:
"Most modern English translations of the Bible render the Hebrew word
chen as 'favour' rather than 'grace'... The King James Version usually renders chen as 'grace' which is more to the point here...
As a kind of universal human concept, 'favour' may be thought of as
being in some way earned through merit or behaviour. Yet the favour of
God that is 'grace' is different than all such human manifestations of
favour, for the grace of God is utterly beyond the resources and power
of man to earn, deserve or purchase." (Ibid., p12)
This is where soteriology comes in - the doctrine of salvation. I quote now from a section in the book below dealing with grace and salvation:
"...evangelical Arminians, Lutherans, and Calvinists agree that human
beings, born in sin, are incapable of any movement toward God apart
from grace. However, Lutheran and Reformed confessions teach that God
not only gives sufficient grace for us to cooperate towards our own
rebirth but actually grants the new birth and faith prior to any human
decision or activity. In other words, our rebirth is monergistic (one
working, namely God) rather than synergistic (cooperation). With
respect to the doctrine of salvation (soteriology), it is this single
point that most decisively distinguishes the churches of the
Reformation from all other traditions.
Key Distinctions: monergism/synergism - Monergism ('one working')
holds that God saves sinners without their assistance, while synergism
('working together') teaches that salvation depends on our
cooperation. In all of its varieties, synergism teaches that God's
grace makes everything possible, but our response makes everything
actual. However, monergism teaches that God's grace accomplishes
everything, even granting us repentance and faith." Pilgrim Theology,
Michael Horton, pp250-251 (Zondervan, 2011)
Finally (though this might best have been the starting point) there is no 'versus' God's grace and the grace of Christ if the Son of God is equally God, as is the Father. It is one and the same grace, decreed by the Father and worked out through Christ as the means, and the gracious operations of the Holy Spirit in applying that to individuals: one God at work regarding his sovereign grace. There is no multiplicity of graces any more than there is a multiplicity of doctrines associated with salvation in the scriptures. Humans have many differing ideas and theologies, but the scriptures uniformly proclaim the one grace of salvation under but one theology. That is why I prefer the KJV rendition of Romans 5:15 -
"For if through the offence of one many be dead, much more the grace
of God, and the gift by grace, by one man, Jesus Christ, hath abounded
unto many."
The emphasis is between 'that of the one offence' and 'that of the one humanity'. There is only one humanity observed in Romans 5:15.
(Which does not bear the meaning 'man' as addressed to Jesus Christ, but 'humanity' that is to say nature, not personal individuality). Aner is the Greek word for an individual male human. Anthropos should usually be translated 'humanity'.
