First off the question your asking is one of the oldest question asked about God. Its often asked like” Why does your loving God allow pain, suffering and death?”
The answer is not a short one so please hang with me; I’ll try to keep as short as possible.
You said you taught Sunday school, so open your bible to Genesis 3:16-17
Let me preference this first by saying God is a loving God. In 1John 4:7-8 it says “Beloved, let us love one another, for love is from God: and everyone who loves is born of God and knows God. The one who does not love does not know God, for God is love.”
Lets go back to Gen 3:16-17 “ And the Lord God commanded the man, saying, “From any tree of the garden you may eat freely; but from the tree of the knowledge good and evil you shall not eat, for in the day that you eat from it you shall surely die.”
Since you’ve taught Sunday school you may know the rest. When Adam and Eve ate every thing changed man fell from walking and communing with God as God set up. Sin, suffering and death entered the world. They did die that day spiritually and one day physically.
God gave man a thing called freewill. He gave us the ability to choose His will for our lives or we can choose are own, He loves us that much He will not make us do anything we don’t want to. Adam chose to eat thus, forever changing the world bringing sin and death into the lives of us that came after him.
His sin affects and infects us all. You don’t teach kids to steal or lie, you teach them not to, we all have now a sinful nature at birth, in a sense we all died spiritually the day Adam ate of the tree. Paul told the church at Rome “ For the wages of sin is death, but the free gift of God is eternal life in Christ our Lord.”
As painful and seemly unfair or unjust as it is we all have an appointment do die. The writer of Hebrews wrote 9:27 and inasmuch as it is appointed for men to die once and after this come judgment” It’s a cold hard fact of life, we all must die young old we will die.
Then we meet God face to face and give an account for our lives for the things we did on this earth. God told the people of Israel “ I call heaven and earth to witness against you today, that I have set before you life and death, the blessing and the curse. So choose life in order that you may live, you and your descendants.” Deut 30:19.
The man who walked into the schoolhouse and shot the Amish girls chose to do so. The men who flue (sp?) the plains into the World Trade Center chose to do so. This world is not how God set it up, man made it this way by his own free will. Sickness and death affects us all because of mans free will.
God knew we would mess it up and choose our own will over His. He new we would need a savior. ‘For all have sinned and fallen short of the glory of God That’s where Jesus comes in We can’t escape the physical death but we can the spiritual one for Rom10:13 “Whoever will call upon the name of the Lord will be saved” I hope this helps
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