In this world, there is opposition. Even children can be attacked by the enemy. Children can have scary dreams, fears and temptations. But, God has given us the power of His might to fend off those attacks. The Armor of God is not just a fun lesson to learn in Sunday School. It's very important to know how to "stand against the wiles of the devil."
The enemy wants us to think that our battle is with other people. But Ephesians 6 goes on to say, "We wrestle not against flesh and blood." Our battle is not with other people but with "powers of the darkness of this world..."
It's important to understand we don't put the armor on by our power. It's God's power, His spirit living inside of us. Just like the plant needs to be healthy for the sap to flow to all parts of the plant, we need God's spirit to flow through us. It's His spirit that protects and guides us.