The contemporary meaning of the term ‘once in a blue moon’ is easier to understand than its origin! Nowadays a blue moon is commonly understood to be an extremely rare occurrence, perhaps never. However, apparently originally it did not refer to a second full moon in a month but to the third full moon in a season with four. The word month comes from moon. The reason the date for Easter varies each year is on account of Easter Sunday needing to be within a week of the first full moon of the spring season. Indeed, the Triune God had seasons in mind when He created the sun, the moon and the stars, ‘Then God said, “Let there be lights in the firmament of the heavens to divide the day from the night; and let them be for signs and seasons, and for days and years’ Genesis 1:14. ‘He appointed the moon for seasons’ Psalm 104:19a.
The Apostle Paul refers to a ‘once in a blue moon’ occurrence where he says, ‘For scarcely for a righteous man will one die; yet perhaps for a good man someone would even dare to die. But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us.’ Romans 5:7-8. Grace is the hardest thing for human beings to understand! Jesus did not lay down His life for the righteous or those who work hard at trying to be good. He died for sinners, i.e. wicked people. ‘As it is written: “There is none righteous, no, not one; There is none who understands; There is none who seeks after God. They have all turned aside; They have together become unprofitable; There is none who does good, no, not one.”’ Romans 3:10-12. My old theological professor used to say something like, ‘Grace is not receiving what you do deserve while receiving what you do not deserve.’
To sin is to break the law, God’s Law, in thought or word or deed. To break God’s Law is to incur God’s penalty, ‘The wages of sin is death’ Romans 6:23a. No human being escapes, ‘For all have sinned and fall short of the glory of God’ Romans 3:23. However, here is the good news, here is the grace of God, in the second half of a verse just quoted ‘The wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord’ Romans 6:23. Eternal life is a gift!
Once in a blue moon will you meet a Christian today who has understood and can articulate that God saves sinners by His grace alone! Salvation is a gift that has been earned by Christ alone and is received through faith alone, ‘For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.’ Ephesians 2:8-9.
What Jesus did on the cross was a ‘blue moon’ occurrence. ‘Not with the blood of goats and calves, but with His own blood He entered the Most Holy place once for all, having attained eternal redemption’ Hebrews 9:12. After celebrating the last Passover (which He transformed into the Lord’s Supper) He was arrested and crucified. As He hung on the tree we are told, ‘Now when the sixth hour had come, there was darkness over the whole land until the ninth hour’ Mark 15:33. We know that this darkness was not a solar eclipse because the Paschal Moon was a full moon. Solar eclipses cannot happen when the moon is full. The darkness symbolised spiritual darkness as the Father turned His face away from His Son on the cross. May He make His face to shine upon you.