Because God is Unchanging...
1: He will always be there (Psalm 90:2; 102:2-27; Isaiah 48:12)
2: His character & ways remain the same (Exodus 3:14-15; 34:5-7)
3: He keeps His word (Isaiah 40:6-8; Psalm 119:89, 151-152)
4: His plans stand firm (1 Samuel 15:29; Numbers 23:19; Psalm 33:11)
5: We can trust Jesus (Hebrews 13:8; 7:24-25)