But whoever drinks of the water that I will give him will never be thirsty again. The water that I will give him will become in him a spring of water welling up to eternal life. John 4:16 ESV
In Jesus’ day, a rain-water cistern was a common source for water. I know about cisterns, because on the farm where I lived as a teenager, that was where our water came from. But having grown up in the city I didn’t realize just exactly how dirty it could become. Then one summer I was asked to clean it when it was almost empty. First, they lowered me down by ropes and then I spent about two hours bailing out the remaining water and scrubbing the bottom with bleach water. I will never forget the mud and other assorted stuff we bailed out, and how great I felt when the following year we had a real well drilled!
The religious experience of many of us is like getting water from a cistern. We go to church on Sunday for a good scrubbing, and then get refilled for the week. After we walk out the door, all kinds of gunk falls in during the week and we need another cleaning by the weekend. But Jesus is offering more than just a good scrubbing now and then. He says that when He enters into our lives, He becomes an unending spring of pure water that leads us to eternal life. Instead of cleaning out and refilling our cistern, Jesus offers to drop spiritual dynamite into our hearts, when we come to His cross. At the cross Jesus once and for all scrubs us clean from our sins and then connects us to the well of living water that gives eternal life. There is no more scrubbing out the cistern when Jesus comes in to drill the well!