How do we know that Jesus's death accomplished salvation?

The accomplishment of salvation through Jesus's death is evidenced in the belief that His sacrifice was effective and intentional, aimed at securing the redemption of His chosen people. Rather than being a mere possibility for all, the Bible teaches that Christ died for His sheep, effectively atoning for their sins (Hebrews 9:15). His declaration, 'It is finished,' underscores the completion and successful nature of His work. Thus, His death was not an effort but an accomplished fact that fulfilled the demands of God's justice, demonstrating that God’s purpose cannot fail.