This thesis investigates the role of the consciousness of sin (suneidesis) within Hebrews' sacrificial argumentation. As a motif, consciousness of sin is a present problem for the recipients. It is a stain that causes dread, timidity, and restricted access. Hebrews' cultic framework naturally interprets this sin as conscious defilement, with this defiling force extending towards the heavenly tabernacle. Hebrews purposefully distinguishes between what Jesus achieves on earth and what he achieves in heaven. Jesus' earthly life of obedience, culminating in death, constitutes his own personal offering; for himself, and for his followers. It enacts a new covenant, redeems, and makes people holy; it deals with the objective issues of sin. Jesus' earthly achievements are many, but only his heavenly blood offering can purge the suneidesis and deal with the ongoing subjective consciousness of sin. Through a ritual and intertextual approach, this study engages, critiques, and advances recent discussions within Hebrews scholarship concerning the location, nature, and timing of Jesus' cultic offering. At the heart of this study is the question of why a heavenly offering is so vital. This thesis concludes that the answer lies in a greater understanding and appreciation of the motif of the "consciousness of sin," and how this is incorporated within Hebrews' cultic argumentation. Hebrews' sacrificial dialogue cannot be emptied of its ritual impact, especially regarding the recipients. Levitical sacrificial ritual--and the notion of asham--offers a conceptual link with Hebrews' notion of the consciousness of sin. Levitical offerings do purify the consciousness, yet they confront it too, by simultaneously reminding people of their sin. The problem of defilement and purgation is not an internal-external juxtaposition, but a qualitative type of purgation which is perpetually offered once by Christ's blood in the heavenly tabernacle. The recipients' consciousness of sin is purged, since they now have perpetual assurance through Christ's heavenly blood, which is speaking continually. This thesis begins with a brief diachronic exploration into the background of suneidesis, as well as outlining the different ways this concept has been interpreted throughout Hebrews scholarship. Part I centres around the problem of suneidesis and the centrality of defilement and the heavenly tabernacle within Hebrews' cultic argumentation. Part II examines Hebrews' cultic argumentation and the solution to a defiled suneidesis. It argues against an overarching Yom Kippur hermeneutic. Instead, Hebrews draws on different motifs to reveal that Jesus' earthly and heavenly soteriological achievements possess their own distinctive purposes. Only Jesus' heavenly blood offering obtains the purgation of the suneidesis. Levitical sacrifice is not supposed to be pitted against Jesus' sacrificial work, instead, it informs the consciousness of sin, as well as the rationality behind Jesus' heavenly blood offering. Part III differentiates between Jesus' session, present heavenly activity, and blood offering. Enthronement celebrates the Son, but Jesus' heavenly blood offering is an independent substance and solution for the consciousness of sin, speaking perpetual purgation over the people of God. Hebrews is concerned less with what Jesus' blood represents, and more with what his blood does and is doing. With boldness and full assurance, and their consciousness and memory of sin erased, the recipients receive perpetual assurance and divine help from their great high priest.