My parents wouldn't freak out either,
Although, including a build like DM Church in this game is quite satanic.
Im not saying its lawsuit worthy, (although it completely is..)
I can see where that mother is coming from. (Hypothetical>>>) I wouldn't want my child playing this game if it had that kinda of atmosphere. We can all admit that the majority of people who play Blockland are pretty young. The only way to find this game on Google, is to search for "Lego building game". And i can only assume that your average 8 year old would be making those kinds of searches.
Gearing the game toward children may not have been your goal. But, as long as this game exists.. It will attract a younger crowed. Removing that save is up to you. But im sure it would improve the over all atmosphere of the game.
But mocking that email? Religions exist wither you like it or not. And offending that religion in a game like blockland, is quite over board in my opinion.