The point Jesus was making is that Nicodemus should have known the truth that the Holy Spirit is the source of new life because it is revealed in the Old Testament. For instance, Moses told the Israelites prior to entering the Promised Land that “The LORD your God will circumcise your hearts and the hearts of your descendants, so that you may love him with all your heart and with all your soul, and live” (Deuteronomy 30:6).
Sinasabi ni Hesus kay Nicodemo na dapat na alam nito ang katotohanan na ang Banal na Espiritu ang panggagalingan ng bagong buhay dahil nahayag na ito noon pa man sa Lumang Tipan. Halimbawa, sinabi ni Moises sa mga Israelita bago sila pumasok sa Lupang Pangako, "At tutuliin ng Panginoon mong Dios ang iyong puso, at ang puso ng iyong binhi, upang ibigin mo ang Panginoon mong Dios ng iyong buong puso, at ng iyong buong kaluluwa, upang ikaw ay mabuhay" (Deuteronomio 30:6).