Why should I give a bowl full of rice to a monk if there is no rebirth?
Buddhism is not an obligatory religion but a religion of voluntary individual participation. There is no obligation to feed monks for non-Buddhists who have not gained appreciation and thus gratitude towards Buddhism.

Monks have carried the teachings over the centuries &amp; established places for dedicated practice. Therefore, grateful Buddhists feeds monks who they have personal faith in &amp; respect for. For example, I once expelled a monk from my home &amp; advised him he was not welcome for alms, because I had no faith in that monk. 

In short, non-Buddhists or non-faithful have no obligation to feed monks.  

Also, Buddhism states monks should be easy to look after &amp; not cause hardship to supporters. In other words, if your family will be deprived due to feeding a monk, Buddhism does not expect you to feed a monk. 


  Dhammapada 49. As a bee gathers honey from the flower without injuring its color or fragrance, even so the sage goes on his
  alms-round in the village.