“We multiply as we are mown down. The blood of the martyrs is the seed of the church.” Translation by nobody in particular.
There were many Christian martyrs in those years too. The Cristero War was fought from 1926 to ’29 against the violently anti-religious forces of Plutarco Elías Calles, President of Mexico 1924-28. I don’t know whether Rivera allied himself with him, but he was an atheist of Sephardic converso ancestry.
A Study of History, Vol VI, OUP, 1939 (footnote)