A blacksmith forges steel by heating it and beating it. God also does this to forge us into mature Christians. He shows us tough love by letting us suffer for our own good.
Many proofs support the gospel. The most compelling of all is suffering. God uses our suffering to advance the gospel like nothing else. When we're faithful to the point of death, the church explodes with growth!
It can be tough to understand why God lets bad things happen. But He uses difficulties in our lives to glorify Himself. He strengthens us to stay faithful because it brings Him glory.