There is an expression in English which says, "Seeing is believing". Interestingly it comes from Jesus' words to doubting Thomas who only believed because he had seen (John 20:29). Jesus went on to say that there is a greater blessing to people who believe the Word of God even though they have not seen. So what then of the people who saw Jesus' miracles? Did they believe? Obviously most did not.
 
Jesus came to His own people but they refused to believe in Him (John 1:11). Jesus condemned those communities for failing to repent and turn to Him. The pagan communities on the coast were more open to the truth; and had Jesus ministered there, He predicted that they would have shown great grief for their sin.
 
The miracles, like every sign from God, only have real meaning when people accept their own smallness compared to God's awesome greatness; and their own sinfulness compared to God's awesome holiness. That is why the miracles should be accompanied by gospel words to explain the meaning of the signs. To benefit from the miracles and hear gospel words, yet fail to repent - is spiritual blindness. They have not understood (seen) who Jesus is and why repentance is the only way forward.
 
It is easy to develop a religious style of Christian faith, where we do the things expected of us, but fail to see ourselves as God does - and fail to repent. Repentance is the only way forwards, not just for now (in our relationship with the Lord) but for eternity, as we anticipate the Day of Judgement. So consider those areas in your life where you have accepted a sin as being normal or even justified. Repent today and rejoice tomorrow. Those who pretend that all is well, when it is not, and rejoice today, will have no opportunity to repent tomorrow.