23 “What do you mean, ‘If I can’?” Jesus asked. “Anything is possible if a person believes.”
24 The father instantly cried out, “I do believe, but help me overcome my unbelief!”
In Luke 5, we see a leper say, "If you are willing, I know you can." Here we see a man who believes Jesus is willing, but questions whether or not He can.
God is capable and caring.
If He were only capable, but didn't care, we would have no confidence in offering up prayers to Him because He'd be all, "I can do whatever I want whenever I want to whomever I want whenever I want to do it and I don't care what you want."
If He were only caring, but not capable, we would have no confidence in offering up prayers to Him because He'd be all, "I love you so much and all, but I'm just one God after all. I wish I could do more for you."