There are four types of bodily discharges mentioned in Leviticus 15, and all four rendered one “unclean” for at least seven days and required sacrifices to be declared “clean” again. The four types of discharge are 1) a chronic male discharge (verses 1–15), 2) emissions of semen (verses 16–18), 3) a woman’s discharge during menstruation (verses 19–24), and 4) a chronic female issue of blood (verses 25–30). The chronic male discharge was most likely due to some kind of venereal disease, so all four bodily discharges have to do with fertility (or periods of infertility) and the proper function of the sexual organs.
The Law does not give a direct reason for the rules concerning bodily discharges, but a verse near the end of Leviticus 15 gives the best hint: “So they will not die in their uncleanness for defiling my dwelling place, which is among them” (Leviticus 15:31). The question naturally arises, why should discharges from sex organs put someone at risk of death for defiling the sanctuary?
The answer is most likely related to the analogy between the “one-flesh relationship” of a man and woman, and the desired relationship between God and His people. The prophets often spoke of idolatry in Israel as “adultery,” in view of the fact that God had chosen Israel as a holy people unto Himself. The rite of circumcision was given to Abraham in Genesis 17. Thus, all the males among God’s people were to be physically marked (on the sexual organ) as set apart for the Lord. Abraham and all his “seed” were to “walk before me faithfully and be blameless” (Genesis 17:1). In light of circumcision as a covenantal sign, an entire chapter devoted to the productivity and proper use of the sexual organs (Leviticus 15) doesn’t seem so out of place.
The very first command to Adam was “be fruitful and increase in number” (Genesis 1:28). After sin entered the world through Adam, Abraham and his miraculous seed were to fulfill Adam’s commission to “be fruitful” as God’s representative on earth (see Genesis 12:2–3). From the beginning, nothing bore greater witness to the God of Creation than the proper means of procreation; so, when the Law was given, the children of Israel were instructed to take seriously the proper and productive use of their sexual organs—all four bodily discharges in Leviticus 15 are “markers” of inappropriate or unproductive use of those organs, just as circumcision “marked” one as a “separated” child of God through the seed of Abraham.
During periods of uncleanness (of which the bodily discharges were a sign), sexual activity was unfruitful and least likely to be honoring to God, and so God forbade physical contact, including sexual activity, with the “unclean.” Leviticus 15 also enforced the ongoing awareness among God’s people of their need to remain set apart for Him alone. In times of uncleanness, God’s people were to have an eager desire to return to full productivity for God’s sake among the nations, given that He had made His “dwelling place” among them (verse 31).
The Law’s added requirement of cleansing and sacrifice once the bodily discharges had ended was primarily to express the individual’s re-consecration to God. The cleansed were “betrothed” to God and spiritually “fertile”; they were “separated” to God and desired to increase their tribe and thus publish God’s name throughout the whole earth.
Christians are not under the Law (Romans 6:14) and are not bound by the Law’s strict requirements concerning circumcision, bodily discharges, and sexual activity. However, we are still a “sanctified” people in that we are set apart in Christ to be holy—we are God’s sanctuary now. As such, we are to behave sexually as those “betrothed” to God and honor Him with our bodies (1 Corinthians 6:12–20; Ephesians 5:18–33).