We know the promise of God is true because He is faithful to His covenant, as demonstrated by the birth of Isaac and fulfilled in Christ.
Romans 9:9 speaks of God's promise to Abraham that he would have a son, demonstrating God's faithfulness to His covenant. Just as Isaac's birth was fulfilled despite human impossibility, God's promises are assured through Christ, the fulfillment of the covenant of grace.
Moreover, believers are assured that every promise made by God will be fulfilled because He is immutable and incapable of failing. As the apostle Paul articulates, God commits to His word and takes action to ensure that His promises come to fruition. This conviction is underpinned by the entirety of Scripture, where God's ongoing faithfulness is continually revealed to His people.
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