As an illustration, find something with a expiration date on it.  Ask the grandchildren what that means.  When they tell you, explain that everything in this life has an expiration date.  Even people have an expiration date on them, we just don't know when that is.  But God does.  That is why in Psalm 90 we can say with the Psalmist:

"So teach us to number our days that we may get a heart of wisdom." (Psalm 90:12)

Over four years ago, I was diagnosed with inoperable stage four lung cancer that had metastasized to lymph nodes, and since then to my liver.  According to my oncologist, I have "beat the odds".  But that is only by the grace of God and the prayers of His people, including all of my grandchildren. (I had three at the time of my diagnosis and five more since then.)

A pastor friend, as well as others, encouraged me to work less so that I could spend more time with our family.  That is when I decided that I wanted to live for my family and see as many grandchildren grow up as the Lord would let me.   How long?  I have no idea.  But today I can.

While I will likely die from cancer, it is my goal to see how long I can live with it...according to God's will.  And that is because of my hope in Jesus Christ.  One of my favorite chapters of Scripture is Romans 5.  It begins:

"Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. Through him we have also obtained access by faith into this grace in which we stand, and we rejoice in hope of the glory of God." (Romans 5:1-2)

I get to share that hope with our grandchildren.  A conversation with them might go something like this: "I know that you have been praying for grandpa to get better for a long time.  I like that you hope and pray for me to get better.  But do you know that there is something that is better than getting better?  And that is being with Jesus.  Because He died on the cross and rose again from the dead, He gives us hope, and life, after death."   While He promises to be with us here on earth.  He promises us that when we die, we will be with Him.

Yes, we all have an expiration date.  But none of us know when that date will be.  So in the mean time we can grandparent with hope.  Hope that we can spend time on this earth with Jesus' promise to be with us always.  But more importantly we live with the sure and certain hope of the resurrection.

I'm reminded of the hymn, "My Hope is Built on Nothing Less", which says:

My hope is built on nothing less Than Jesus' blood and righteousness; No merit of my own I claim but wholly lean on Jesus' name. On Christ the solid rock I stand; All other ground is sinking sand.

When darkness veils His lovely face, I rest on His unchanging grace; In every high and stormy gale My anchor hold within the veil. On Christ the solid rock I stand; All other ground is sinking sand.

His oath, His covenant and blood Support me in the raging flood; When every earthly prop gives way, He then is all my hope and stay. On Christ the solid rock I stand; All other ground is sinking sand.

When He shall come with trumpet sound, Oh, may I then in Him be found, Clothed in His righteousness alone, Redeemed to stand before the throne! On Christ the solid rock I stand; All other ground is sinking sand. 

An object lesson you can do with your grandchildren to illustrate what our hope is built on: Get two big tubs of similar size (or use the same one twice). Put some sand in one of them.  Put two similar sized rocks in the other tub.  In one tub build two sand towers and connect them with a plastic (perhaps Duplo) bridge.  Make a bridge between the two rocks in the other tub.  Dump a bucket of water into both of them and see which one holds up.

Relate that to "On Christ the solid rock I stand; all other ground is sinking sand."  You could also sing with them, "The wise man built his house upon the rock," children's song. At a distance? You could make "Grandparent videos" of these illustrations, or sing the songs together via video chat.

Prayer:  Lord, in the midst of our own struggles help us to demonstrate hope to our children and grandchildren, showing that You are our only hope.  Amen.

How do you share our sure and certain hope with your grandchildren? Comment below.