THE short answer to the question, ‘Why is the Bible called the Testament?’ is—
Because it testifies the mind or will of GOD.
But, as not only the English and Roman law confine the word Testament to a disposition of goods, made previous to death; but the Apostle Paul also expressly applies it in the same sense to the Scriptures, Heb. ix. 16. I apprehend it would not be quite satisfactory to your theological readers, to leave them only with the plain English of the word Testament.
It appears, then, that St. Paul, the inspired promulger, or rather confirmer, of this term, to the commencement of the Christian dispensation, does so expressly, on the ground of its PERISHABILITY—but yet, perishable for a moment only, that it may revive to eternity; for, in I Cor. xv. 36. it is laid down as a principle extending from a grain of wheat to CHRIST , that, that which is sown, is not quickened, except it die.
Next, Christianity is the sphere, which issued from Christ, before his final separation from the earth. Now, the atmosphere must certainly gradually dissipate, after the removal of the body, from whence it proceeded. Some may say, Is not this philosophising contradicted by the promise, concluding St. Matthew’s gospel—‘I am with you always, unto the end of the world?’—I answer, The world ceases when Christianity, its vital principle, its truth, order, cement, ceases. But the unlearned ought to know, that the promise literally is this—‘I am with you always, unto the consummation of the age.’
But the consummation, entire, of the old, is immediately followed up by the commencement of the new. When the grain of wheat perishes, it sprouts, and progressively brings forth fruit an hundred fold.