By the Blessed Surgeon Saint Luke, Archbishop of Simferopol
Every time before Christ healed someone, He asked that person if he believed. And only if he believed, He performed the miracle.
Every time a miracle occurs, the Holy Spirit acts, and for someone to receive the Holy Spirit an open heart is necessary, and it is made open by faith. Just as the reception of radio waves necessarily requires an antenna, similarly for the reception of divine grace a pure heart full of faith is needed.
Our Lord does not impose His grace on anyone. One asks for faith, hope and love and only then does the Lord give His grace: when by faith one's heart is opened before Him. This happening is a great mystery, and this mystery happened every time Christ performed miracles.
The Holy Apostle Paul says that all the essence of the gospel message is found in hope, faith and love. Consequently, it is necessary that we have a strong and steadfast faith for us to be Christians and inheritors of divine grace.
If you believe that the electron exists without seeing it, then by what right do you say that our faith in God, Who also has not been seen by anyone, is unreasonable?
I will say that we too know God by His energies; by the manifestations of His power; by how He acts in our hearts; by the grace that we feel. Not anyone can prove faith. Many have tried to prove that God exists and many that He does not exist. But never has anyone been able to prove one or the other. Only with a pure heart can one see God....
Faith is the most valuable treasure on earth and we must guard it more than anything else.