"Believe on the Lord Jesus Christ and Thou Shalt Be Saved." But, What Does It Mean "to Believe"? Questions About the Saving of the Thief on the Cross Help Us Cut Away the Clutter and Come to the Pith. So, Simply Put: That Thief Put His Trust in What Jesus Said, and He Was Satisfied; He Said Nothing More. How We Come by Assurance of Our Salvation (Chiefly by Knowing the Lord Jesus).