Is God's Gift of Salvation Permanent?

For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, that no one should boast. (Ephesians 2:8–9)

Our response in salvation is faith, but even that is not of ourselves [but is] the gift of God. Faith is nothing that we do in our own power or by our own resources. In the first place we do not have adequate power or resources. More than that, God would not want us to rely on them even if we had them. Otherwise salvation would be in part by our own works, and we would have some ground to boast in ourselves. Paul intends to emphasize that even faith is not from us apart from God’s giving it. . . .

http://www.macarthurcommentaries.com