Why is the concept of Jesus's testament important for Christians?

The concept of Jesus's testament is vital for Christians as it highlights the assurance of their inheritance as children of God. Through His testament, believers are promised not only temporal and spiritual blessings but also the hope of eternal life. The depth of this relationship is characterized by Jesus referring to His followers as His family — His bride, His brothers, and His children. This relational dynamic emphasizes the importance of being 'joint-heirs' with Christ, which is foundational to understanding the depth of salvation and the richness of God's sovereign grace bestowed upon His people.