How do we know that God's promises are unconditional?

The nature of God's covenants, as seen from Psalm 89, is that they are unconditional, particularly the covenant with Christ. This is evident in God's promise to establish Christ's kingdom without conditions related to human performance. For example, while God anticipates sin and potential disobedience, His commitment to fulfill His covenant through Christ remains unaltered. As the psalm illustrates, mercy and faithfulness are established forever by God's decree, showcasing that His promises do not depend on human actions but are grounded in His sovereign will. The assurance of these promises flows from the eternal relationship between the Father and the Son.