The issue of how “works” figure into our salvation is a much debated and confusing issue. On one hand Paul says salvation is not of works less men should boast about it. Then we note James who said our works demonstrate our faith, which many see as essential to salvation. Additionally in John’s Gospel, Jesus says that faith is a work. So what is the truth of the matter; are we saved by works of some sort or not?
I suspect that the problem is largely a failure to recognize that salvation has two aspects. One involves our God relationship. The other aspect, sanctification, entails our maturing as spiritual beings created in the image of God.
Our God relationship, which defines us a worthy and acceptable in God’s eyes, does not involve any human effort whatsoever, no works period. No faith. No obedience. No knowledge. Nothing at all. The only possible way to be worthy and acceptable to the Creator would be for him to unilaterally define us as such. A divine declaration of worth and acceptance cannot be earned, appropriated, or rejected for that matter. No one by commission or omission can logically overrule God’s will and divine purpose, which is clearly stated in the Bible.
Sanctification or spiritual development does involve human effort, a lot of it mental, i.e. rejecting old assumptions and beliefs in favor of the counter intuitive commandments of Jesus. This process is the incorporation of the mind of Christ, in the words of Paul.
So God acceptance is a fact because God wills it so, not because we decide to be acceptable through proper works. Sanctification, however, is a large part of why we are here in the first place, to work out our salvation with fear and trembling. Growing in the spirit is indeed hard work.