I know wedding cakes don't usually have writing on them, this is a different situation. My aunt asked me to do a small cake for my cousin's wedding that a priest is blessing on Sunday before my uncle passes, since he is not going to make it to the actual wedding in July. Any ideas on what to write other than Congratulations Name and Name?
Since you are having a priest bless the cake, would you want to do some bible verses? such as from Corinthians 'And now these three remain: faith, hope and love. But the greatest of these is love.' or John 'Beloved, let us love one another, for love is from God; and everyone who loves is born of God and knows God.' I could see a sweet small handwriting for the verse, then a larger Congratulations Name and Name.
Or how about just a smaller version of the real thing, since the uncle won't get to see it.
On my daughter's bridal shower cake, instead of congratulations or best wishes, I wrote the words, "With this ring..." Or you could complete the saying if you have the room to put, "With this ring, I thee wed.".