Pronunciation of 大罪

Question

There's a Japanese manga/anime series called Nanatsu no taizai (七つの大罪, ), which is pronounced as

ななつのたいざい

as one can clearly hear in this intro or see in its Wikipedia page.

However, the word 「大罪」is pronounced as「だいざい, as I've found in both a dictionary and Wikipedia page for cardinal sins.

Why is the pronunciation in the show different?

Answer 1

たいざい is just an alternative reading of 大罪, and is listed perhaps in all decent monolingual dictionaries.

• デジタル大辞泉 and 明鏡国語辞典 treat たいざい as the primary reading and だいざい as an alternative.
• 大辞林 treats だいざい as the primary reading.