How do we know that God's mercy is effectual?

The assurance of effectual mercy stems from the nature of God Himself; He cannot fail to accomplish what He sets out to do. Throughout scripture, God demonstrates His unwavering commitment to His promises, and His mercy towards His people exemplifies this. In the case of the Israelites, their release from Egyptian captivity fulfilled God's foreordained purpose, evidenced by the prophetic promises He made to Abraham. Thus, effectual mercy is not dependent on human action but is rooted in divine sovereignty. God's counsel will stand, and His mercy will unfailingly bring His chosen people to salvation.