Someone who out-performs the majority of Christians with extraordinary works and extends compassion towards others outwardly, could do so with great consistency without ever having claimed to believe in Jesus Christ. They could demonstrate what appears to be fruitful behavior through their works and actions without having faith that brings justification.
On the other hand, a believer in Jesus Christ may have faith without demonstrating it outwardly in ways that we or certain religious people think that it should be expressed. But that doesn't mean they are not saved and justified. The effort to produce and then boast in works is not proof of faith. Faith is the evidence of that which is not seen. Perhaps this is why Paul said we look at what is not seen ... because justification and righteousness is granted to those who-do-not-work but believe in Him who justifies the ungodly.
Over the years, we've heard from believers who attended church regularly and would often walk out of the building wondering if they were still saved. They heard a works-based message which planted fear and doubt because they would begin questioning whether they were "doing enough" to guarantee their salvation. Certain people from the legalistic department who self-identify as judgmental "fruit inspectors" will suggest that some who have confessed Jesus Christ and called on the name of the Lord "didn't really mean it" and therefore, did not have a genuine conversion. They will point to works as the manifested proof in the pudding. But they fail to provide the specifics—or it will vary greatly among the denominations.
The blessed assurance or guarantee we have is found within the person of Jesus Christ and belief in Him. Although we are created in Christ for good works—God working in and through us—salvation is a gift by grace through faith (apart from works) and is not the result of any effort on our part. As Paul said in Romans 4:5: "But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness."
