How does the concept of justification by faith work?

Justification by faith is a core tenet of Reformed theology, rooted in the belief that God declares a sinner righteous based on their faith in Jesus Christ's sacrificial work. This is exemplified in Romans 4:5, which states, 'But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.' This judicial act of God absolves believers from the penalty of sin and grants them the righteousness of Christ, thereby allowing them to stand blameless before Him. It underscores the complete sufficiency of Christ's atonement, rendering any effort to attain righteousness through the law ineffective.