The disciples witnessed Jesus anoint the blind man with clay made of saliva and dirt, but they did not witness him receive his sight (Jn. 9:6-34). It was not until after his testimony of what Jesus did for him was rejected, that the Lord's disciples saw him healed (Jn. 9:35). Of course, the blind man's healing was evidence to His disciples of His identity, but it also illustrated the blindness of the religious leaders (Jn. 9:39-41).
Like most of us who know Jesus as our Lord and Savior, the blind man had to come to an understanding as to who Jesus was, before he responded with saving faith. He, like all of us, knew He was a man (Jn. 9:11). He, like we, realized that His words were truth, and that He was therefore a prophet (Jn. 9:17). The text does not say that he, himself, knew Jesus was the Messiah of Israel, but we can make that assumption because his parents did (Jn. 9:18-23). I doubt that any born again believer, at the same stage in the salvation process, had a problem believing Jesus was supposed to be Israel's King. And like this healed blind man, when we came to the realization that Jesus is the Son of God, our response is to worship Him (Jn. 9:35-38)! Our hearts were blind, but they were opened to Jesus by the working of the Holy Spirit (Jn. 3:3-8; 16:13)!
Every saved person has a testimony; tell people how you received your sight!