Praise be to Allaah.
Firstly:
We Muslims fast the month of Ramadaan because Allaah has commanded us to do so. Allaah says (interpretation of the meaning):
“ O you who believe! Observing As-Sawm (the fasting) is prescribed for you as it was prescribed for those before you, that you may become Al-Muttaqoon (pious)”
[al-Baqarah 2:183]
So we worship Allaah by doing this act of worship which is beloved to Allaah and which He has enjoined upon us.