The soteriological theory of Jobs salvation is no theory at all or speculation, but the same throughout all of history.. And the same for every sinner born into this world regardless of where you are or what religious background u hold to. And that is, by the free mercy of Gods grace in the righteousness of Christ alone. Salvation and righteousness belongs to God alone. Grace and life is in Christ alone. The book of Job brings out Gods Sovereignty over all creation. His supreme will that directs all things. It properly shows where man belongs, in the dust. It cuts to the heart of mans sinful depravity and destroys mans self righteous pride and will. The book of Job shows how Job, through the brokenness of his own sin, although in rt standing with God, glorified God for His mercy. He was resting in Gods mercy and acknowledged He (God) alone is righteous. This is evidence of a man saved by Gods grace and mercy! And shows how God is Sovereign over Satan, man and all of creation, to glorify Himself. His Holy will stands supreme. And through Jobs calamity, he realized this and was faithful to the end; thanx be to Gods Sovereign mercy and love He chose to show in Job. So where is man for him to boast in anything? The more we created sinful beings seek to credit our desires, actions, works, and will to our acceptance towards God, the further we fall from grace and the righteousness of faith in Christ. Regardless of how sincere a Muslim is, he is still lost and dead in his sin and under Gods wrath. Christ, who is fully God and Supreme creator can only be the assurance of ones despair over their sin.