Why was there such a horrible defeat in chapter 4 at the hands of the Philistines? We thought the Philistines were the bad guys, yet they won the battle. This was not because God was on their side, but rather because God was dealing with the sins of Israel. The priests were sinning. There was a level of comfort developing that they almost are beginning to believe that as long as they have the Ark of the Covenant and God is on their side they cannot lose. They foolishly thought this would be the case no matter what they did. But God was greatly concerned about their obedience and living in a way that honored God.
What would the lesson be if they could sin greatly and still be blessed in battle? This was a horrible day in the history of Israel. The high priest Eli, who was by all measures a godly man though he did not do well at disciplining his sons the priests died at the news of his sons' deaths and the capture of the Ark of the Covenant.
Eli's grandson is born about this time. This child should be the eventual replacement for his father Phineas, but Phineas died because of the evil practices he continued to carry out in direct violation of God's commands. The name Ichabod is given to the child which means "no glory" symbolizing that the glory of the LORD has departed because of the sins of Israel, the Ark of the Covenant representing His presence is no longer with them. Now is a time for repentance and humbly turning back to the LORD. 30,000 soldiers died in that battle. That must have been a real wake up call. God took his hands off Irael for that moment and let them be defeated by the Philistines. None of this would have happened if they would simply just obey. Yet, God is gracious and if they truly repent and turn back to Him there will be forgiveness.