@EndTimes, love your faith and insight! Faith is a gift from God, not based on our own intellectual consent to His miracles, but of the Holy Spirit testifying to us that He is who He says He is. We should not demand signs, but receive the Kingdom of God like little children with trust. And the Father draws us to Christ through the Holy Spirit, for those He predestined, He also called. (And those He called He also justified, and those He justified, He also glorified

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However, I do think the purposes of His miracles are vast. Jesus is infinitely merciful and compassionate and wanted to heal people out of love, and He also wanted to show that He has the authority to forgive sins (in the case of the man with the mat, like you said!) and use the miracles to teach lessons (like when He made the fig tree wither) and to prove that the Father is in Him, and possibly to increase the faith of the apostles and all His flock. For in John 10:38, it says
“But if I do them, even though you do not believe me, believe the works, that you may know and understand that the Father is in me, and I in the Father."
And in Luke 17:20-23, “ When the men came to Him, they said, “John the Baptist has sent us to You, to ask, ‘Are You the Expected One, or do we look for someone else?’” At that very time He cured many people of diseases and afflictions and evil spirits; and He gave sight to many who were blind. And He answered and said to them, “Go and report to John what you have seen and heard: the blind receive sight, the lame walk, the lepers are cleansed, and the deaf hear, the dead are raised up, the poor have the gospel preached to them. Blessed is he who does not take offense at Me.”
It seems as though He was showing that by His miracles, it affirmed that He is who He says He is. Do you think He also may have done the miracles to strengthen their faith, along with many other reasons? We certainly should not demand more signs than the sign of Jonah now, though, because we have trustworthy testimonies telling us of all He did.