The 'redeemer' here is the go'el — the kinsman-redeemer, the protector of the family. The fatherless child's redeemer is God Himself. He is mighty and will plead their cause. This is a strong deterrent: whoever wrongs the vulnerable will face God as their opponent.
Memory phrase: God defends the helpless.
Talk about it: How does it feel to know God stands up for people who are alone and helpless?
Prayer: God, thank You for defending those who have no one.