We must believe that God exists and that He rewards those who seek Him
Hebrews 11:6 (ASV 1901)
6and without faith it is impossible to be well-pleasing unto him; for he that cometh to God must believe that he is, and that he is a rewarder of them that seek after him.
An old unbelieving chief makes up his mind to find God after the painful loss of his son. Mary Slessor led him in prayer to become a Christian.