Faith does not come from ignorance. Faith is based on what we know.
Before we will trust others with something precious to us, we first try to find out if they are trustworthy. This father was asking that he might come to know God in such a dimension that he could trust Him to cure his son.
His son had been possessed by an evil spirit since early childhood. The father did not know Jesus well, but he had heard and seen enough to convince him that if there was any hope for his son, it lay with Jesus. In desperation he cried out to Jesus for help. Jesus’ response was to heal his son. The desperate father had correctly gone to Jesus with his problem even though he was struggling with his faith.
When you are struggling to believe, that is not the time to avoid Christ or to be ashamed of your struggle. You will never increase your faith by not going to Jesus! Rather, Jesus wants to help you with your belief. He can not only meet your need, but He will also give you faith to trust Him to provide for you.
If you are struggling to believe that God can take care of your need, it is because you don’t know Him as He wants you to. Go to Him and allow Him to convince you of His ability to meet every need you will ever face.