Those who need signs and wonders to believe in Jesus are doubters, like Thomas, he had to put his hand in Jesus wound to believe it was Jesus even though He was right there.

True believers trust in the word of God because of their faith. The nobleman in the story believe that Jesus could heal his son and because of his faith, his son was healed without Jesus going to where he was. Because Jesus died for us, His grace and mercy is sufficient to take us through. The love God has for us and the promises He makes to us if we live faithful life, is enough sign to sustain us.