The demand is “to be born again or anew”. The logic is simple. It is when one is begotten by a human father that one becomes part of human kingdom. So too to enter the kingdom of God, one is to be begotten by heavenly Father. It is through Jesus who reveals the Father that this is made possible.
In the Old Testament, Israel with whom God made the covenant is considered “the Son of God” (Ex 4: 22; Deut 22: 6; Hos 11: 1). The anointed king of Israel was considered the “Son of God” (2 Sam 7: 14; Ps 2: 7; 89: 27). In the later period, the Israelites are called “sons of God” (Wis 5: 5). The sonship is understood both in the present and future sense. These ideas are found in the New Testament too. There are texts in which the sonship is considered as future status (Lk 20: 36; 6: 35). In the Gospel of John, the sonship is already experienced on earth and is perfected after death. The means to this sonship is the “begetting” by God. This is the birth “from above”. The teaching is similar to becoming like children, as mentioned in the Gospel of Matthew 18: 3.