Shared ground
Nicodemus is presented as an informed, socially respected Jewish leader who approaches Jesus seriously, using Jesus’ signs as evidence that God is with him (vv. 1–2). Jesus does not stay on the topic of signs. He turns to what is required for someone to “see” and “enter” God’s kingdom: a person must be “born anew” (v. 3) and, restated, “born of water and the Spirit” (v. 5). Nicodemus initially hears this in a straightforward physical sense and finds it impossible for an older person (v. 4). Jesus’ clarification contrasts two sources of life: what comes from “flesh” stays on the human level; what comes from the Spirit is Spirit-origin life (vv. 6–7).
Where interpretation differs (only where needed)
“Born anew” (“again” or “from above”): The wording can be heard as being born again (a new start) or being born from above (from God). The passage itself supports both ideas: it is a new beginning that cannot be produced by ordinary human means.
“Born of water and the Spirit”: Readers disagree about what “water” refers to. Some take it as natural birth (water as part of human birth), so Jesus is contrasting physical birth with Spirit-given birth. Others take “water” as pointing to a cleansing act God provides, so “water and Spirit” together describe one divine work of renewal. Others connect “water” to baptism as an outward sign tied to entry into the community, while still emphasizing that the Spirit is the decisive giver of this new life.
Why the disagreement exists
John’s wording is brief, and “water” can signal more than one background idea in Jewish and early Christian language (birth imagery, cleansing imagery, or baptismal practice). Also, Jesus’ style in this Gospel often uses layered language that invites more than one association while still aiming at a central point: new life is needed, and it comes from God’s Spirit, not from human ability.
What this passage clearly contributes
This scene ties “signs” to a deeper issue: recognizing that God is with Jesus is not the same as being able to perceive and participate in God’s kingdom (vv. 2–3). Entry into God’s kingdom requires a kind of birth that is not merely human (“flesh”) but Spirit-given (vv. 5–6). The text also shows how Jesus’ teaching can be misunderstood if taken only at the surface level (v. 4), and it frames “new birth” as necessary, not optional (vv. 3, 5, 7). See also John 1:12–13.