“Waiting for the adoption.”
Even in this world saints are God’s children, but men cannot discover them to be so, except by certain moral characteristics. The adoption is not manifested, the children are not yet openly declared. Among the Romans a man might adopt a child, and keep it private for a long time: but there was a second adoption in public; when the child was brought before the constituted authorities its former garments were taken off, and the father who took it to be his child gave it raiment suitable to its new condition of life. “Beloved, now are we the sons of God, and it doth not yet appear what we shall be.” We are not yet arrayed in the apparel which befits the royal family of heaven; we are wearing in this flesh and blood just what we wore as the sons of Adam; but we know that “when he shall appear” who is the “first-born among many brethren,” we shall be like him, we shall see him as he is. Cannot you imagine that a child taken from the lowest ranks of society, and adopted by a Roman senator, would say to himself, “I long for the day when I shall be publicly adopted. Then I shall leave off these plebeian garments, and be robed as becomes my senatorial rank”? Happy in what he has received, for that very reason he groans to get the fulness of what is promised him. So it is with us today. We are waiting till we shall put on our proper garments, and shall be manifested as the children of God. We are young nobles, and have not yet worn our coronets. We are young brides, and the marriage day is not yet come, and by the love our Spouse bears us, we are led to long and sigh for the bridal morning. Our very happiness makes us groan after more; our joy, like a swollen spring, longs to well up like an Iceland geyser, leaping to the skies, and it heaves and groans within our spirit for want of space and room by which to manifest itself to men.
Spurgeon, C. H. (1896). Morning and evening: Daily readings. London: Passmore & Alabaster.