Why must you be married before you can “multiply and replenish the earth”? A non-member asked me this and I don’t know the answer. So would you please answer this for me?
So often we are asked to probe the mind of God. It would seem to me that a sufficient answer to many questions would be, “Because God said so.” Until the restoration of the gospel in 1830, all that the world had of the word of God was the Bible. Although a relatively large book, the Bible is not a manual of doctrinal instruction. It is an after-the-fact collection of the writings of many people over a period of more than 1500 years. With the restoration of the gospel there has been and continues to be a flood of revelation from God to man.
Your question comes from the commandment given to Adam and Eve as reported by the prophet Moses. Here is the account from Genesis,
So God created man in his own image, in the image of God created he him; male and female created he them.
And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth (Gen 1:27-28).
A question would be, was it necessary for Adam and Eve to be married in order to have children? Since God also said, Thou shalt not commit adultery (Ex 20:14), it must be concluded that Adam and Eve were indeed married. God Himself gave them to each other. So why was such emphasis put on marriage as an essential precursor to indulging in the procreative act? Bringing children into mortality is one of the most sacred functions in which mankind can participate. It is an essential step in the continued progress of our Father’s children to grow to an eternal maturity to become like He is. Because of its extremely sacred nature the adversary of mankind has done all he can to destroy the sanctity of marriage and the generation of offspring. According to the plan of God for the welfare of man, children are to be born into a home of loving parents, who will nurture and care for them, training them to avoid the pitfalls of life and to prepare themselves to return with honor to the presence of their Father in Heaven. All of the instructions, helps and aids for that sacred mission of parents are contained within the principles of the gospel of Jesus Christ and within the organization, activities and programs of The Church of Jesus Christ of Latter-day Saints. There can be no more joy, fulfilment, value and happiness in any other walk of life.