How do we know God's mercy is guaranteed?

In the sermon, it is stated that God's declaration of mercy is not uncertain; He definitively states, 'I will have mercy.' This aligns with His character as the eternal 'I Am,' and underscores the belief in God's sovereign grace. Can we claim a guarantee for this mercy? Absolutely, as Scripture consistently affirms that God delights in showing mercy rather than wrath. Therefore, it's rooted in His immutable nature that those chosen by Him will not be left to themselves but will receive His mercy in their lives.