Because it is contained in Scripture, "Behold, I lay in Zion a chief cornerstone, chosen, and precious: He who believes in him will not be disappointed."
He that believeth The Prophet does not say in him, but declares generally, “He that believeth shall not make haste.” As, however, there is no doubt but that God sets forth Christ there as the object of our faith, the faith of which the Prophet speaks must look on him alone. And, doubtless, no one can rightly believe, but he who is fully convinced that in Christ he ought wholly to trust. 