Genesis 22:2 Then God said "Take your son, your own son, Isaac, whom you love, and go to the region of Moriah. Sacrifice him there as a burnt offering on one of the mountains I will tell you about."
The verse before this says "Sometime later God tested Abraham."
God tests our faith not for God's own good to see if we believe, if we have faith, because he already knows what we are going to do. He tests our faith so we can prove to ourselves what faith and how much faith we have in God. He allows circumstances or ordains events that give us opportunity to prove our faith to ourselves.
Honestly, this would be a hard one for me if God asked me to do this. I have one son, one daughter, I love both. I worry more about the son and have spent countless hours in prayer for his safety. He has had some rough life learning moments that each time God has allowed him to stumble, but never completely fall. Looking back on them, I can see God "had his back" in each of them and each event did build my faith more in God.
My earnest prayer is that my son will be used mightily for God's glory, but am I willing to "go the distance" if what will cause God great glory will be a tremendous sacrifice to me in pain and suffering, like those parents who have lost children to cancer or other events, yet through those circumstances people have come to know God. I would like to hope I would have the faith of Abraham. That if God directed or God ordained, I would get up early the next morning like Abraham did (Genesis 22:3) and start on their journey to obey God. And though I know God will not ask me to physically sacrifice my son on an altar, I know he could ask me to surrender him entirely to God and to allow God to work mightily in his life for God's glory. I know I surrender him to God, but take him back soon after. I hope one day to have Abraham's faith, knowing and trusting God is in control and knows what is best for my children for his glory, no matter what the cost to me.
After all, he was willing to give his son, his one and only son, whom he loves very much to the world so that we would be able to spend eternity with him.
John 3:16 For God so loved the world that he gave his one and only Son that whoever believes in Him shall not perish, but have eternal life."