There are spiritual wars going on in the spirit world continuously. We know this from the book of Job and Daniel. Light and Darkness or if you prefer Good and Evil are at constant battles.
Satan has power. God is all-powerful. Satan wants to get people's thoughts and hearts away from God. We know from the Bible that after Jesus' 1000 year millenial reign, Satan is cast into the lake of fire with other non-believers, liars, the false prophet, and others.
If God allowed evil, to take away His only Son from this earth by nailing Him to a cross, then God is protecting those children, not by physical protection but rather from spiritual protection. Jesus does not promise to those who live on the earth a pain-free, trouble-free life. He does promise in Luke this: Lk 21:17 All men will hate you because of me.
Lk 21:18 But not a hair of your head will perish.
Lk 21:19 By standing firm you will gain life NIV
He is not talking about physical hair but your eternal, spirtual hair. The life you gain is not physical life but eternal life with the Father, Son, and Spirit.
Prayers are a powerful tool against evil. You prayer ofter to fight evil. Revelation states---Rev 5:8 And when he had taken it, the four living creatures and the twenty-four elders fell down before the Lamb. Each one had a harp and they were holding golden bowls full of incense, which are the prayers of the saints and again in
Rev 8:3 Another angel, who had a golden censer, came and stood at the altar. He was given much incense to offer, with the prayers of all the saints, on the golden altar before the throne.
Rev 8:4 The smoke of the incense, together with the prayers of the saints, went up before God from the angel’s hand.
The Holy Bible