Read John 8:48-9:34: Seven years ago I traveled to India on a mission trip visiting Syam and Esther and ZEC Ministries. In preparation for going on the trip our team had extensive training on praying for others as when you go to India nearly everyone at the different churches will want you to pray for them. They want you to pray a blessing over them or for you to pray for healing, expecting a miracle. We heard many testimonies of people who had gone to India before who had seen miraculous healings take place and I remember being very nervous about all that because I had never seen God work a miracle through me.
While in India what they told us would happen happened. Whenever we went to visit a church many individuals would come to us Americans and ask for prayer. I remember at one church an older lady came to me while many others of our team were praying for others and she didn't speak English and there wasn't anyone to translate. She put her hands together in prayer and then touched her right shoulder and her side and her face and then bowed her head, expecting me to start praying. I worked up the courage and laid my hand on her shoulder and started to pray and when I finished praying she looked up at me with the biggest smile. Pastor Syam walked over and talked to her and she said that through my prayers God had healed her. She had issues with her whole right side after a stroke and after receiving prayer, she felt better than she had in years with more mobility, less pain, and clearer vision. Through my prayers God healed her and I was blown away, who am I that God used me to heal this woman.
In this passage in John, Jesus heals a blind man but the "religious" people around him doubt where his ministry comes from. God was working through Jesus and God is still working today to do miracles but many "religious" people do not believe this is possible and condemn other Christians for praying for healing and miracles to take place.
I have seen God heal people today in India and here in the States and those healings are from God not from the devil. I want to encourage you to pray for healing and to not let others, be they believers or non-believers, discourage you from doing so.