Before John of Damascus was Isaiah. Isaiah 1 whole chapter but in particular verse 14. The moon is NOT relevant in the occurrence of the Spring equinox. And any Christian should know that when the flesh dies the soul returns to the Maker that sent it. It was the 'passover' death of the perfect Lamb that gives anyone who will the act of redemption for life eternal.
It is a wee bit curious how that there are prophecies given to the children of light in days (solar) and then about those in terms of months (lunar). Now you can attribute it to a state of 'fear', but I will call it reverence to appointed times that flesh men willingly ignore.
Before John of Damascus was Isaiah
But between them both was the Incarnation of Christ.