The connection between marriage and children. It is a sensitive subject, for a whole range of reasons, and can be deeply difficult, given the impact of the Fall. Writing about love and companionship in marriage is easier, since everyone agrees with that. But we also need to hear Scripture's teaching on marriage and children.

Scripture teaches that God wants the offspring of Adam and Eve reigning over the earth, to His glory. So God designed marriage, for children. Perhaps this is an uncomfortable truth, but it is biblical, and pastorally important.

Genesis 1-3 is foundational for all of life, and it connects marriage to children. The command is "be fruitful, multiply..." More detail is given, but this much is incontrovertible. Calvin puts it simply: "Adam with his wife was formed for the production of offspring".

At the level of detail, we need to be careful not to read into the text. For example, the text does not say that Adam was "lonely", but "alone", or "single". Adam's upcoming marriage is not merely about meeting emotional needs. Similarly, the text implies "one-spirit", but what it emphasises is "one-flesh" ­physically unified. The text pursues its own interest in marriage, which interest centres on fruitfulness (cf. Gen 3:16, "you will bear children").

Malachi hits the nail on the head. He asks, "Why one-flesh?" The answer: "God seeks godly offspring" (2:15). It parallels Genesis, adding "godly" for clarification. Children should be raised in the "fear and admonition of the Lord" (Eph 6:4). God "instituted marriage, so that legitimate and pure offspring might be brought forth" (Calvin).

This is big-picture Old Testament teaching. It is no small point. With Genesis 1-3, Malachi forms the bookends of the Old Testament. Both have "blessing" a worldwide family, a pure temple or Eden, a fruitful land, the enemy trampled underfoot, the Messiah, and marriage.

Are we fulfilling the vision? The Australian birth-rate is about 1.8. We are not even replacing ourselves. Yet God is looking for "godly seed" — a vast number of people from all nations who will be trained in His purposes.

Does God change His mind in the New Testament? Some say that "Be fruitful" is "fulfilled by Jesus", which sounds good but doesn't help. Rather, while there are exceptions to the norm for those with special gifts and ministries, the New Testament follows the Old Testament vision. Consider the following.

The New Testament repeatedly says "one-flesh". That invokes the whole Old Testament context.

Fatherhood is divine. God is Father (pater), so "every family" is a patria, the ancient, patriarchal household (Eph. 3:15).

Motherhood is a virtue. It is assumed, and commanded (Titus 2:4; 1 Tim. 5:14). Women are "saved through childbearing" (1 Tim. 2:15) — typically a normal part of life in Christ.

Some think Ephesians 5:22-33 gives marriage a new, alternative or higher purpose. Marriage mystically illustrates union with Christ. However, Paul denies that marriage is a "mystery" (5:32; not RSV). Union with Christ is mentioned only as a "powerful example" of "the obligations of marriage" (Calvin. See also Luther's Babylonian Captivity).

What of childlessness, infertility, and all of the tragedies of reproduction? This brings very real grief. Is it wrong or hurtful to say that marriage is about children? Actually, this is necessary knowledge. The connection explains sadness at childlessness. Children are in our DNA, as it were, but the Fall has marred the creation. The companionship of marriage gives comfort in these circumstances (1 Sam. 1:8).

Some express it this way. In marriage, there is "openness to life". That is helpful. Plan to have children, help with grandchildren, consider adoption and fostering, support other families, and pursue wider service.

Marriage is personally enriching, but it is not about bartered self-fulfilment. Couples even look outside themselves, seeking a "godly-seed". This is a calling from God.