I have a question about God saying be fruitful and multiply: Is it a command or a genetic code or a part of us that is put into us that is not a choice? Or is it both? The reason I ask is that all the old covenants are gone. Paul says it's ok to be single under certain circumstances of that time of persecution. I know it's given a time frame, but if be fruitful and multiply was a command would it be nullified by the new covenant? Or is be fruitful and multiply not a covenant but a thing that is just instilled? Something I thought of to look at and I don't know if he is saying it is a command or a covenant or something.
The command "be fruitful and multiply" (Genesis 1:28) was given to mankind when God created the world. It wasn't a part of a covenant directly. Because it was a command to mankind as a whole, it still exists, just as the command to marry in Genesis 2:24 still exists -- verified by Jesus (Matthew 19:4-6). Along with that command was that mankind is to have dominion over the world. That still exists. The consequences to Adam and Eve's sin also continue to this day (Genesis 3:16-19).
The other place this command appears is in the covenant with Noah (Genesis 9:1). That covenant, in which God promised not to destroy the world by water, is still in effect. The rainbow is still around. Mankind still has the right to eat animal flesh (I Timothy 4:4). We still are forbidden to eat blood (Acts 15:29). Murder still requires a death penalty (Romans 13:4). That covenant was between God and all mankind.
What did end was the covenant God made with Israel -- the law of Moses. "Behold, the days are coming, says the LORD, when I will make a new covenant with the house of Israel and with the house of Judah - not according to the covenant that I made with their fathers in the day that I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the LORD" (Jeremiah 31:31-32). That covenant was made with just one nation and God said it was a temporary covenant.
Now, does this mean that everyone should have as many kids as possible? No. God wanted mankind to fill the earth, that is something we have done, so the command is being followed whether people acknowledge God's dominion or not. What Paul pointed out in I Corinthians 7 is that there are times when it is a better thing to avoid or delay marriage, such as in times of persecution. Even in those times, marriage remains a good thing to do, it is just that in certain times, the single life can become a better choice. Yet, overall, the command to be fruitful and multiply is still being followed by mankind as a whole.