Catholics kiss their thumb after making the sign of the cross. Why? And how did this begin?
I do not know where this originated but it is not very rampant where I live. However, in my travels and in some movies I have seen, I observed the same. I asked a number of Hispanic friends I have and they confirmed they learned by watching their parents or guardians; they weren’t specifically taught to do this in catechism classes or any place they received Catholic formation.
The reason they kiss their thumb is they’re making the sign of the cross with their forefinger finger and their thumb. So, they technically aren’t kissing their finger, but kissing the Cross they make. This is not a bad practice since it is a sign of reverence to the Cross of Christ. It is just like how we learned to kiss the Cross on our Rosaries before praying the Chaplet.
The practice of kissing the Cross is an ancient custom showing a person’s devotion to Christ and also acceptance of one’s own life’s burdens. If done with presentness of mind and reverence, I am sure this could be a source of blessing and grace.