Why is it said that believers overcome by the blood of the Lamb?

The phrase 'they overcame him by the blood of the Lamb' highlights the centrality of Christ's sacrifice as the cornerstone of salvation and victory over sin and Satan. This reference not only points to the efficacy of the atoning work of Christ but also depicts the believer's reliance on His righteousness rather than their own. The blood symbolizes redemption and the defeat of the accuser, asserting that through faith in Christ’s sacrificial death, believers find assurance and strength to face adversities. Therefore, it is through Christ alone that believers are granted victory in spiritual warfare.