Why is Christ described as a cornerstone in Isaiah 28?

In the biblical context, a cornerstone is integral to the stability and alignment of a structure. Christ is referred to as the cornerstone because He brings the Church together, marking its dimensions and uniting all believers regardless of their background. Isaiah indicates that both Old and New Testament saints are bound together in Christ. This unity is foundational to the Church, ensuring it remains strong and aligned with God's purposes. His role as cornerstone reflects His central position in both salvation and the communal life of the Church.