God gave us the ability to be creators ourselves, and also commanded us to have children and to populate the earth. The very first mitzvah to appear in the Torah is the commandment to have children. God blessed them and God said to them, “Be fruitful and multiply, fill the earth and subdue it…”
This verse teaches us that God commanded Adam and Eve to have children. According to Jewish law, a couple has not fulfilled this obligation until they have had two children (preferably a son and a daughter).
Based on the following verse in the book of Isaiah, it is considered appropriate to have more children, if possible. “He is the God, the One Who fashioned the earth, and its Maker. He has established it … He did not create it for emptiness; He fashioned it to be inhabited…”
The most obvious reason for this commandment is God’s desire that we populate the world and create people who can observe the Torah and fulfill the purpose of Creation.
Having children also helps the individual archive his purpose in creation, by improving his character. Nurturing, caring for and educating children encourages the development of sympathy, mercy and sensitivity to others.
Having a child is also one of the ways in which we can emulate the kind of altruistic giving that God demonstrated when He gave us life. Just as God created a world for the purpose of giving, just as He sustains and cares for the world, so a parent creates a child, gives the child, sustains it and cares for it. The act of creating a child is thus analogous to God’s creation of the world.