Baptism is holy, and a sacrament, because it is a sign and a memorial that the man can be regenerated by the Lord, by means of truths from the Word,—a sign for heaven, and a memorial for man; and that a man is introduced by it into the church,—as the children of Israel by passing over the Jordan were introduced into the land of Canaan, and as the inhabitants of Jerusalem were prepared by the Baptism of John for the reception of the Lord. For without that sign in heaven before the angels, the Jews could not have subsisted and lived at the coming of Jehovah, that is of the Lord, in the flesh. (A. R. n. 776.)
The Baptism of John prepared the heavens, that the Jewish people might subsist when God Himself should appear among them. (Letter to Beyer, Swed. Doc., p. 170.)
John was the prophet who was sent to prepare the way of Jehovah God, who was to descend into the world and accomplish the work of redemption. He prepared that way by baptism, and then by announcing the coming of the Lord; and without that preparation all there would have been smitten with a curse, and would have perished. (T. C. R n. 688.)
The reason why a way was prepared by John's Baptism was, that by that baptism they were introduced into the future church of the Lord, and in heaven were inserted among those there who expected and desired the Messiah, and so were guarded by angels, lest devils should break forth from hell and destroy them. . . .
If the way had not been prepared for the descent of Jehovah into the world by means of Baptism, the effect of which in heaven was that the hells were closed, and the Jews were guarded from total destruction [they would have perished]. (ib. n. 689.)
After quotation and exposition of some illustrative and confirmatory passages from the Word, the author adds:—
These few examples illustrate with what a curse and destruction the Jews would have been smitten, if they had not been prepared by the Baptism of John to receive the Messiah, who was Jehovah God in the human form, and if He had not assumed the Human and so revealed Himself. And they were prepared by this, that in heaven they were enrolled and numbered among those who in heart expected and desired the Messiah; in consequence of which angels were then sent, and became their guardians, (ib. n. 691. See also A. E. n. 724.)