It is faith that rescues us from sin and its consequences—misery here and eternal punishment in hell. Of course, it isn’t faith that actually saves; faith is the means by which the saving work of Jesus Christ on the cross is mediated to the one who is saved (“rescued”). One is saved by grace through faith.
Faith isn’t faith in the abstract. It is dependence upon the Gospel. It means so believing in the truth that Jesus Christ died in his place, for his sins, that one stakes his eternal welfare upon that Gospel. If Jesus could fail (which He won’t), he’d go down with Him!
So, saving faith is faith in the good news that sinners need to hear. The Gospel is good news to be believed; not good works to be accomplished. All that needed to be done to save His own, Jesus has already done. Nothing need be, or could be, added to it. The person who is eligible to be saved is the one who recognizes that he isn’t eligible—on his own. Only Christ can make him so. His part is to admit his sin, his inability to rescue himself from sin and hell, and trust in what Jesus has already accomplished.