There was once a bridge which spanned a large river. During the day the bridge sat with its length running up and down the river parallel with the banks, allowing ships to pass through freely. But at certain times each day, a train would come and the bridge would be turned sideways across the river, allowing a train across it.
A switchman sat in a small shack on one side of the river where he operated the controls to turn the bridge and lock it into place when a train crossed. One evening as the switchman was waiting for the light of the day to come, he looked off into the distance thru the dim twilight and caught sight of the trainlights. He stepped to the controls and waited until the train was within a prescribed distance within the bridge. He turned the bridge into position, but, to his horror, found the locking control did not work. If the bridge was not secure in position, it would wobble back and forth at the ends when the train came on to it, causing the train to jump the track and go crashing into the river. This would be a passenger train with many people aboard.
He left the bridge turned across the river, and hurried across the bridge to the other side of the river where there was a lever switch that could hold to operate the lock manually. He would have to hold the switch back firmly as the train crossed. He could hear the rumble of the train now. He took hold of the lever and kept applying pressure to keep the mechanism locked. Many lives depended on this man's strength.
Then, coming across the bridge from the direction of his control room, he heard a sound that made his blood run cold. "Daddy, where are you?" His four-year-old son was crossing the bridge to look for him. His first impulse was to cry out to the child, "Run! Run!" But the train was close; the tiny legs would never make it across the bridge in time.
He almost left his lever to run and snatch up his son and carry him but he realized that he would not be able to get back to the lever in time. Either the people on the train or his little son must die.
He took a moment to make his decision. The train sped safely about, on its way, and no one aboard was even aware of the tiny broken body, thrown mercilessly into the river by the onrushing train. Nor were they aware of the pitiful figure of the sobbing man, still clinging tightly to the locking lever long after the train had passed. They did not see him walk home more slowly than he had ever walked: to tell his wife how the child had brutally died.
Now if you comprehend the emotions which were in this man's heart, you can begin to understand the feelings of our Father in Heaven when He allowed His Son to bridge the gap between us and eternal life. Can there be any wonder that He caused the earth to tremble and the skies to darken as His Son died? How does He feel when we speed along thru life without any thought to what was done for us through Jesus Christ?
When was the last time you thanked Him for the sacrifice of His Son?
If this story is used in a lesson, it would be wise to explain that it is not totally correct because unlike the boy in the story, the Savior himself knew and chose to make the sacrifice, though it still helps the listener to understand the pain of God the Father.