Dedicated to the Lord Jesus Christ Who loved us, gave Himself for us, and washed us from our sins in His own Blood; and to the Church, which is His body.

Thomas refused to believe what He couldn't see or feel. Our five senses were given to us by God and are necessary to help us function in this life. But if we do not renew our minds to acknowledge the limits of our five senses, they will keep us from believing spiritually. Faith can perceive things that the senses cannot (Hebrews 11:1).
There is a human faith and a supernatural, God-kind of faith. Human faith is based on physical things that we can see, taste, hear, smell, or feel. God's kind of faith believes independently of physical circumstances. To receive God's gift of salvation, we have to use the supernatural, God-kind of faith which isn't limited by our five senses. This is because, to be saved, we must believe for things that we can't see or feel. We haven't seen God or the devil. We haven't seen Heaven or Hell. Yet we have to believe that these things exist. Human faith can't believe what it can't see.
Man is so destitute that he can't even believe the gospel on his own. To receive God's gift of salvation, we have to receive the supernatural, God-kind of faith first. 
Romans 10:17 says, "So then faith cometh by hearing, and hearing by the word of God." God's Word contains His faith. As we hear the Word of God about salvation, We receive God's faith so that we can believe the good news of our salvation. We actually use God's faith to get saved.
This God-kind of faith doesn't leave us after our born-again experience.
God's faith becomes a fruit of the Spirit which is in our hearts. We never lose this supernatural faith. We just have to renew our minds to God's faith which is in us, and then learn how to use it.