"Then the Lord said to Moses, 'Go in to Pharaoh and say to him, ‘Thus says the Lord, “Let my people go, that they may serve me.'" Exodus 8:1

God's people had become slaves. Humanly speaking, their sin was to blame. But God sovereignly had them there and He was the only one who could free them. That is what God does when a person puts their trust in the finished work of Christ at the cross. God frees us to serve Him. It is glorious freedom when the Son sets you free.