How do we know that Jesus' sacrifice is the only means of salvation?

Hebrews 9:24 clarifies that Christ did not enter into the earthly tabernacle but into heaven itself, thus acting as our mediator: ‘For Christ is not entered into the holy places made with hands, which are the figures of the true, but into heaven itself, now to appear in the presence of God for us.’ This reinforces the understanding that salvation is only through Him, as He offered Himself as the perfect sacrifice, fulfilling the requirements of the law and forever establishing a new covenant with His blood. The uniqueness of Christ’s sacrifice is foundational to Reformed theology, which emphasizes that salvation is entirely by grace through faith in Jesus Christ alone.