Church bells developed out of the monasteries. They existed for the same reasons muezzins do in Islam, they serve as a reminder of 'jesus' to go to worship and to remind the monks of their 'tasks'. This was co-opted from Roman bathing periods that were announced by bells, a kind of theft of a secular meaning put into a 'religious' one of 'cleansing'.
A lot of the meaning of Saturday and Sunday was stolen and reintrepreted along similar lines as well.