There are many points to be made clear in your letter: first, as to Heb. 12, it has nothing to say to continual cleansing; "the blood of sprinkling" is a general expression drawn from Judaism, blood being so used for cleansing. But it is used in contrast to Abel's blood which cried for vengeance, Christ's for mercy, and indeed speaks of prospective millennial blessing, and the gathering together in one of all in heaven and earth. That the blood of Christ remains in perpetual value before God, I do not doubt a moment; but, spiritually speaking, it has been sprinkled, and that is presenting it to God, not sprinkling it on anything of ours.
But the great point which wants clearing up is confounding imputation and communion and its interruption. 1 John speaks of fellowship or communion, not of imputation. The priesthood in Hebrews is not for sins, save in the one great act of reconciliation-it is for mercy and grace "to help in time of need" (chap. iv.)-for the simple reason that "by one offering he hath perfected forever them that are sanctified" through it; and "forever" signifies without break or intermission: as He is sitting constantly (Heb. 10:12) at the right hand of God, we are constantly perfect. (Ver. 14.) Hence "the worshippers once purged should have no more conscience of sins."
As to sins after conversion, the whole thing is a mistake, leaving out Christ's work, and thinking of the state of our conscience and the Spirit's work in us. The sins we have committed can alone be on our conscience, but as to the effectual work that puts them away, all our sins were future when Christ bore them. Did He bear our sins up to the day of our conversion and not after? If so they never can be forgiven at all, and we must be lost; He cannot die any more; "for then must he often have suffered." Read. Heb. 9; 10, which treat these questions elaborately.
Washing with water is quite another thing; it is the application of the word by the Holy Ghost. Once thus born, that work cannot be repeated, but the least word or evil act interrupts communion, and the soul must be restored to communion. So Christ is Advocate to this effect; but there (1 John) fellowship is treated of; and the ground of this advocacy, instead of imputation, is, that the righteous One (our righteousness) is always there, and the blood of propitiation always valid. We are in Christ, and there is no condemnation for those who are in Him; and in another aspect He always appears in the presence of God for us. The sprinkling of the leper does not affect the question: there was no repetition of fault for renewed cleansing; it was, when cured, the ground of all restoration to communion. Sins are worse after believing, for it is sinning against known love; and the measure of responsibility is greater; we are "to walk as he walked," and manifest the life of Jesus in all things. Nor is anything passed over. Advocacy may restore, and we judge ourselves-else we are judged, chastened that we may not be condemned. I think it is a mistake to apply "the blood of Jesus cleanseth us" to past or present faults. It is an abstract statement, as I may say, Medicine cures the ague. "If we walk in the light, as he is in the light," is the same; it is the Christian's place as such. "Hearts sprinkled from an evil conscience," etc. (Heb. 10:22), refers, I have no doubt, to the priest's consecration which was done once for all. The value of Christ's blood was the ground for everything, we cannot account of it too highly; but it was the golden plate with "holiness to the Lord" which met the iniquities of their holy things.
I believe I have answered from scripture all that you inquire of, or given what meets them all, at least. If anything remains not cleared up, I shall be glad to write again. It is well for the saints to be clear on these things, and in these days especially.
December, 1873.