Why is the concept of a witness altar important for Christians?

The concept of a witness altar is significant for Christians as it represents the assurance of our faith and the communal aspect of worship. In Joshua 22, the altar served as a public declaration of the unity of the Reubenites, Gadites, and half-tribe of Manasseh with the rest of Israel, signifying a collective identity in worshiping the one true God. This concept finds its fulfillment in Christ, who serves as our ultimate witness through His sacrificial death and resurrection, allowing believers to boldly proclaim their faith. As Hebrews 10 indicates, the law was merely a shadow of greater realities found in Christ, allowing our worship to transcend old covenant rituals and pointing to a permanent connection with God through Jesus. Hence, this 'altar' becomes symbolic of the grace and unity we have in Christ.