There is an important section of the Stromata Book 4 that we should consider also. Clement, of course, is the author of the letter to Theodore which mentions the secret gospel. In the Stromata Book 4 there is an important discussion of nakedness which makes extended references to 2 Corinthians 5:3. But the ultimate context is the (secret?) gospel and its relationship interesting to Ezekiel chapter 44. Why Ezekiel 44? It is strangely about 're-establishing' the priesthood in Jerusalem at the time of Ezekiel. Interesting that Clement in To Theodore implies the 'mystery of the kingdom of God' in the passage in the Secret Gospel is also tied to the establishment of priests in the Church (of St Mark) in Alexandria.
Let's begin with the passage in Ezekiel. It specifically mentions a seven day purification period after 'baptism':
Therefore thus saith the Lord God; No alien, uncircumcised in heart or uncircumcised in flesh, shall enter into my sanctuary, of all the children of strangers that are in the midst of the house of Israel. But as for the Levites who departed far from me when Israel went astray from me after their imaginations, they shall even bear their iniquity. Yet they shall minister in my sanctuary, [being] porters at the gates of the house, and serving the house: they shall slay the victims and the whole-burnt-offerings for the people, and they shall stand before the people to minister to them. Because they ministered to them before their idols, and it became to the house of Israel a punishment of iniquity; therefore have I lifted up my hand against them, saith the Lord God. And they shall not draw nigh to me to minister to me in the priests' office, nor to approach the holy things of the children of Israel, nor [to approach] my holy of holies: but they shall bear their reproach for the error wherein they erred. They shall bring them to keep the charges of the house, for all the service of it, and for all that they shall do. The priests the Levites, the sons of Sadduc who kept the charges of my sanctuary when the house of Israel when astray from me, these shall draw night to me to minister to me, and shall stand before my face, to offer sacrifice to me, the fat and the blood, saith the Lord God These shall enter into my sanctuary, and these shall approach my table, to minister to me, and they shall keep my charges. And it shall come to pass when they enter the gates of the inner court, [that] they shall put on linen robes; and they shall not put on woollen garments when they minister at the gate of the inner court. And they shall have linen mitres upon their heads, and shall have linen drawers upon their loins; and they shall not tightly gird themselves. And when they go out into the outer court to the people, they shall put off their robes, in which they minister; and they shall lay them up in the chambers of the sanctuary, and shall put on other robes, and they shall not sanctify the people with their robes. And they shall not shave their heads, nor shall they pluck off their hair; they shall carefully cover their heads. And no priest shall drink any wine, when they go into the inner court. Neither shall they take to themselves to wife a widow, or one that is put away, but a virgin of the seed of Israel: but if there should happen to be a priest's widow, they shall take [her]. And they shall teach my people [to distinguish] between holy and profane, and they shall make known to them [the difference] between unclean and clean. And these shall attend at a judgment of blood to decide it: they shall rightly observe my ordinances, and judge my judgments, and keep my statutes and my commandments in all my feasts; and they shall hallow my sabbaths. And they shall not go in to the dead body of a man to defile themselves: only [a priest] may defile himself for a father, or for a mother, or for a son, or for a daughter, or for a brother, or for his sister, who has not been married. And after he has been cleansed, let him number to himself seven days. And on whatsoever day they shall enter into the inner court to minister in the holy place, they shall bring a purification, saith the Lord God. And it shall be to them for an inheritance: I am their inheritance: and no possession shall be given them among the children of Israel; for I am their possession.
Now let's look at the first passage in the Stromata Book Four which references the nakedness of 2 Corinthians 5:3:
Wherefore thus says the Lord, Every alien son is uncircumcised in heart, and uncircumcised in flesh (that is, unclean in body and soul): there shall not enter one of the strangers into the midst of the house of Israel, but the Levites. Ezekiel 44:9-10 He calls those that would not believe, but would disbelieve, strangers. Only those who live purely being true priests of God. Wherefore, of all the circumcised tribes, those anointed to be high priests, and kings, and prophets, were reckoned more holy. Whence He commands them not to touch dead bodies, or approach the dead; not that the body was polluted, but that sin and disobedience were incarnate, and embodied, and dead, and therefore abominable. It was only, then, when a father and mother, a son and daughter died, that the priest was allowed to enter, because these were related only by flesh and seed, to whom the priest was indebted for the immediate cause of his entrance into life. And they purify themselves seven days, the period in which Creation was consummated. For on the seventh day the rest is celebrated; and on the eighth he brings a purification, as is written in Ezekiel, according to which purification the promise is to be received. Ezekiel 44:27 And the perfect purification (τέλειος καθαρισμὸς), I take it, is that propitious faith in the Gospel (τὸ εὐαγγέλιον πίστις) which is by the law and the prophets, and the purity which shows itself in universal obedience, with the abandonment of the things of the world; in order to that grateful surrender of the tabernacle (εὐχάριστον τοῦ σκήνους ἀπόδοσιν), which results from the enjoyment of the soul. Whether, then, the time be that which through the seven periods enumerated returns to the chiefest rest, or the seven heavens, which some reckon one above the other; or whether also the fixed sphere which borders on the intellectual world be called the eighth, the expression denotes that the Gnostic ought to rise out of the sphere of creation and of sin. After these seven days, sacrifices are offered for sins. For there is still fear of change, and it touches the seventh circle. The righteous Job says: Naked came I out of my mother's womb, and naked shall I return there; Job 1:21 not naked of possessions, for that were a trivial and common thing; but, as a just man, he departs naked of evil and sin, and of the unsightly shape which follows those who have led bad lives. For this was what was said, Unless you be converted, and become as children, Matthew 18:3 pure in flesh, holy in soul by abstinence from evil deeds; showing that He would have us to be such as also He generated us from our mother— the water. For the intent of one generation succeeding another is to immortalize by progress.
So Clement understands that Jesus's mission on earth was to establish mysteries of purification which resembled those which accompanied the restoration of the priesthood at the time of Ezekiel. In what follows he declares that we must ultimately go from the seventh to the eighth which he likens to a transfer from 'physical character' (φυσικωτέρων) to :
The Saviour Himself, then, plainly initiates us into the mysteries, according to the words of the tragedy: —
Seeing those who see, he also gives the orgies.
And if you ask,
These orgies, what is their nature?
You will hear again:—
It is forbidden to mortals uninitiated in the Bacchic rites to know.
And if any one will inquire curiously what they are, let him hear:—
It is not lawful for you to hear, but they are worth knowing;
The rites of the God detest him who practices impiety.
Now God, who is without beginning, is the perfect beginning of the universe, and the producer of the beginning. As, then, He is being, He is the first principle of the department of action, as He is good, of morals; as He is mind, on the other hand, He is the first principle of reasoning and of judgment. Whence also He alone is Teacher, who is the only Son of the Most High Father, the Instructor of men.
What are these mysteries that Jesus initiates the initiate into according to Clement? He answers - "I shall pray the Spirit of Christ to wing me to my Jerusalem." Clearly then Jesus initiates the initiate into a heavenly ascent but specifically a heavenly ascent involving ritual nudity.
Now why would Clement reference Ezekiel at the very beginning if this was not relevant to the discussion? What we have to begin to see is that baptism is at the beginning of the seven day period of purification. Look back and see for yourself. In Ezekiel 44:26 - 27 it says explicitly:
And after he has been cleansed, let him number to himself seven days. And on whatsoever day they shall enter into the inner court to minister in the holy place, they shall bring a purification, saith the Lord God.
Clearly Clement in the Letter to Theodore connects the 'after six days' in Secret Mark with entering the holy of holies in the temple too albeit now the Church of St Mark in Alexandria. Now let's see how he ties in 2 Corinthians 5:3 in what follows in Stromata Book 4
Now the soul of the wise man and Gnostic, as sojourning in the body, conducts itself towards it gravely and respectfully, not with inordinate affections, as about to leave the tabernacle if the time of departure summon. I am a stranger in the earth, and a sojourner with you, it is said. And hence Basilides says, that he apprehends that the election are strangers to the world, being supramundane by nature. But this is not the case. For all things are of one God. And no one is a stranger to the world by nature, their essence being one, and God one. But the elect man dwells as a sojourner, knowing all things to be possessed and disposed of; and he makes use of the things which the Pythagoreans make out to be the threefold good things. The body, too, as one sent on a distant pilgrimage, uses inns and dwellings by the way, having care of the things of the world, of the places where he halts; but leaving his dwelling-place and property without excessive emotion; readily following him that leads him away from life; by no means and on no occasion turning back; giving thanks for his sojourn, and blessing [God] for his departure, embracing the mansion that is in heaven. For we know, that, if the earthly house of our tabernacle be dissolved, we have a building of God, an house not made with hands, eternal in the heavens. For we that are in this tabernacle do groan, desiring to be clothed upon with our house which is from heaven: if so be that being clothed we shall not be found naked. For we walk by faith, not by sight, as the apostle says; and we are willing rather to be absent from the body, and present with God. The rather is in comparison. And comparison obtains in the case of things that fall under resemblance; as the more valiant man is more valiant among the valiant, and most valiant among cowards. Whence he adds, Wherefore we strive, whether present or absent, to be accepted with Him, 2 Corinthians 5:9 that is, God, whose work and creation are all things, both the world and things supramundane. I admire Epicharmus, who clearly says:—
Endowed with pious mind, you will not, in dying,
Suffer anything evil. The spirit will dwell in heaven above;
and the minstrel who sings:—
The souls of the wicked flit about below the skies on earth,
In murderous pains beneath inevitable yokes of evils;
But those of the pious dwell in the heavens,
Hymning in songs the Great, the Blessed One.
The soul is not then sent down from heaven to what is worse. For God works all things up to what is better. But the soul which has chosen the best life— the life that is from God and righteousness— exchanges earth for heaven. With reason therefore, Job, who had attained to knowledge, said, Now I know that you can do all things; and nothing is impossible to You. For who tells me of what I know not, great and wonderful things with which I was unacquainted? And I felt myself vile, considering myself to be earth and ashes. For he who, being in a state of ignorance, is sinful, is earth and ashes; while he who is in a state of knowledge, being assimilated as far as possible to God, is already spiritual, and so elect.