A Muslim follows the teachings of Prophet Muhammad (may Allah's peace and blessings be upon him) and prays in the exact manner the Prophet used to pray.
The testimony of faith, which includes testifying the Creator's oneness and worshiping Him alone along with testifying that Muhammad is His slave and messenger.
Although we could see the rainbow and the mirage, yet they do not actually exist. Moreover, we believe in the existence of gravity without seeing it just because its existence was proven by the material science.
