How do we know that Christ's death bears fruit?

In John 12, Jesus uses the metaphor of a seed falling into the ground and dying to illustrate the necessity of His death for the bearing of fruit. His death leads to His resurrection, which is the first fruit that secures eternal life for His people. In Romans 5:21, it is emphasized that grace reigns through righteousness, leading to eternal life through Jesus Christ. This means that Christ’s death is never in vain; it produces spiritual life in all for whom He died, and those who are united with Him will ultimately bear fruit that glorifies God.