In Genesis 1:28, God commands his faithful adherents to be fruitful and multiply, which is to say have lots of kids: 4, 5, 6, 7, 8, 9, or even 10 children. Being fruitful and multiplying by having a big family is all well and good, but at what point ought the world start reproducing less frequently? The UN estimates that the world population will reach 11 billion people by 2100, and the growth of humanity won’t cease unless something catastrophic happens such as mass starvation or a disease epidemic. You can view the source here: Projections of population growth - Wikipedia