Absolutely not. A showing of faith is better than no faith at all.
ST762
What if they are prayed to a Hindu god or Budda or someone like that?
A non Christian means someone not having faith in Jesus Christ nor believing that Christ is their Lord and Saviour. So most likely a non Christian would not be praying to Jesus for your benefit. In that case they would be praying to some other God like budda, or allah. So I would tell them not to bother wasting their time nor their breath.