It is not unusual to hear someone say, "I'm no saint," or "I'm just a sinner saved by grace." It is true that Paul refers to himself as the "chief" or "foremost" of sinners (I Tim. 1:15). In that passage, however, he seems to be talking about his life before his encounter with Christ on the road to Damascus, for he next says that he "obtained mercy" (in the past tense). On the other hand, sixty times in the New Testament, the followers of Jesus are referred to as "saints" or "holy ones" (almost always in the plural, for Jesus is the Holy One). We sometimes say we want to speak where the Bible speaks and use Bible names for Bible things. How is it then that we refrain from calling ourselves the saints?
It is certainly true that we do sin and that we are saved by the grace of God. However, how we view ourselves has an impact on how we live our lives. If, when we are tempted to sin, we imagine ourselves as sinners saved by grace, we may think, "Well, I'm just a sinner. God's grace will cover me if I do this." Then we go ahead and sin because we imagine ourselves as sinners. But if we imagine ourselves a being saints, then we think, "I'm one of God's holy people set apart for Him and I can't let myself do this." There is a reason why scripture so often calls us saints and so seldom calls us sinners. The mindset of saints allows us to resist the devil so that he will flee from us.