"I will believe if God will appear to me."

A proud and ignorant sinner who says this has no understanding of the nature of His Creator. No man has ever seen the essence of God. (When God "appeared" to certain men in the Old Testament, He manifested Himself in other forms, such as a burning bush or "the Angel of the Lord.")

When Moses asked to see God’s glory, God told him, "I will make all my goodness pass before you,...[but] you cannot see my face: for there shall no man see me, and live" (Exodus 33:18–23). If all of God’s "goodness" were shown to a sinner, he would instantly die. God’s "goodness" would just spill wrath upon evil man. However, the Lord told Moses, "It shall come to pass, while my glory passes by, that I will put you in a cleft of the rock, and will cover you with My hand while I pass by." The only way a sinner can live in the presence of a holy God is to be hidden in the Rock of Jesus Christ (1 Corinthians 10:4).