God has promised that he can would save anyone that would call on him. Romans 10:13

God promised I will never leave thee nor forsake thee. Hebrews 13:5

God promised he would come back. John 14:1-6

You may say, he promised that a long time ago but let me tell you that what God promises he will do. Just like it was promised that he would be born and it happened, he would die, and it happened, he would rise again, it happened so will the second coming happen.

God promises to forgive our sin when we confess our sin. 1 John 1:9

God promises to answer our prayers James 4:1-2; Jeremiah 33:3 but he also promises if iniquity is in our hearts he won't hear us Psalm 66:18

God always does what he promises to do!

Lamentations 2:17 KJV
The LORD hath done that which he had devised; he hath fulfilled his word that he had commanded in the days of old: he hath thrown down, and hath not pitied: and he hath caused thine enemy to rejoice over thee, he hath set up the horn of thine adversaries.