Our entire Christian life is built on promises, including those for eternal life and resurrection. These promises are either unconditional or conditional. God will fulfill certain promises regardless of the circumstances. Other times, He will do something only if we meet certain conditions.
Dr. Stanley explains why we know God will keep His promises—because He is truthful, faithful, immutable, and loving. Also, we can trust in His ability to keep those promises because our Lord is:
Omniscient: God knows everything about every decision we need to make. He knows what came before and what comes after. His promises to us are based on complete knowledge, so He doesn’t make mistakes. 
Omnipresent: God is always with us no matter what’s going on in our lives.  He promises to never leave nor forsake us. 
Omnipotent: El Shaddai is the Hebrew name for God that means “God Almighty.” He is always in control whether we understand what He is doing or not. Nothing is too difficult for Him.
The only reasons a conditional promise might not be fulfilled is because our requests aren’t in the will of God or sin has gotten in the way. For these promises, God only requires two things from us: obedience and faith. If we follow the Lord and trust Him to keep His word, we will experience the great blessings of His fulfilled promises.