This discussion will only consider the use of birth control within marriage, as all forms of sex outside of marriage constitute either fornication or adultery and are clearly contrary to the teaching of scripture.
Also, this discussion will only cover methods of birth control that prevent conception. I would argue that once an egg is fertilized, we have a human life (see Psalm 139:12-15 for instance). Therefore, forms of birth control that either destroy a conceptus or prevent it from implanting (such as RU486 or IUDs) destroy a developing human life and violate the Seventh Commandment.
The Basic Argument
While there is a general scriptural commandment to multiply and be fruitful within scripture (Gen. 1:28), this commandment is not absolute as to persons or number, and therefore it does not constitute a sin for a married couple to use birth control to limit the number of children they have, or the time at which they are born.
In farming, while we have a God given duty to use the land to provide a harvest, we are not called upon to merely sow seed continuously and without method in a way that would ensure crops are always growing but would exhaust the ground and eventually produce sickly and blighted harvests, but rather we are to use our God given reason in the process and employ divinely appointed methods such as crop rotation and allowing the ground to lie fallow (Exodus 23:11, etc.) that we might produce a better and healthier harvest later on. I would argue that there is no reason the same logic cannot apply to child bearing. As John Jefferson Davis, Professor of Systematic Theology at Gordon Conwell has written:
“Man, as a conscious being, is to direct all his powers including his procreative ones, towards their appointed goals, with guidance of the principles revealed in Scripture. Man’s calling is not simply to let “nature take its course,” but to consciously redirect nature toward the fulfillment of the divine plan. Just as God himself created the human race and re-created a fallen humanity according to a conscious plan. So it would follow that man, as God’s vice regent on earth, should imitate God by exercising his procreative gifts according a conscious plan. God did not create by a blind act of passion and will; neither should those made in his image.” (Davis, Evangelical Ethics, p.56)
The argument that our animals deserve a break from laboring, and even our land requires a break from producing harvests, but that our wives may never have a break from bearing our children seems wrong-headed to me.
Now, this is not to argue that a married couple can choose to use birth control to ensure that they never have children. Voluntarily remaining childless within marriage is clearly contradictory to the teaching of scripture and goes against one of the primary purposes of marriage – i.e. The raising up of Godly offspring (Mal. 2:15). This is not akin to allowing a field to remain fallow for a season, but a decision to never plant and thus never produce a harvest.
Some other Considerations Related to the Above
1) The idea that “Natural Family Planning” is good, while artificial barriers such as condoms or diaphragms are evil is simply insupportable. The aim of both methods is to allow for sexual relations without that sexual contact producing children. Both methods do so by making sure that semen and egg do not come together. One via the artificial manipulation of time and the other via the use of an artificial barrier. I would actually argue from 1 Cor. 7:5 that because “Natural Family Planning” requires total abstinence for a time, and for a reason other than prayer, it is actually more unnatural than the simple use of a barrier device and far more likely to result in the intermittent “burning” that marriage is supposed to prevent (1 Cor. 7:9).
Additionally, while I would argue that it is impossible for man to thwart the will of God, if the use of birth control devices such as condoms genuinely thwarts his will, then “natural family planning” must as well for all the same reasons.
2) The idea that the creation mandate of Genesis 1:28 requires all people to have as many children as they possibly can cannot be supported from scripture. Scripture clearly says that there is nothing wrong with the decision to remain single for the sake of the Kingdom (Matthew 19:12, 1 Cor. 7:7), and this was the course taken by Jeremiah, John, Jesus, Paul, etc. Therefore, there is no absolute requirement for ALL people to multiply and be fruitful.
3) Additionally, the idea that we are called to “maximum fertility” is contradicted by the fact that Christian couples may renounce sexual relations “for a time” for the purposes of prayer and fasting, as well as the biblical example of apostles and Christians who pursued callings that necessarily took them away from their wives for a period of time.
4) We should also acknowledge that sex within marriage was intended as God’s good gift regardless of whether it produces children and is to be enjoyed by infertile couples and couples beyond childbearing age. Additionally, the fact that a man and a woman know that (humanly speaking) they will not be able to have children should not preclude them from marrying. In such cases it may be God’s will that their own family (like His own – see Rom. 8:15, Gal. 4:5, Eph. 1:5) be formed via adoption.
All in all, it is difficult, if not impossible, to argue that the biblical imperative is for all people on earth to marry and have as many children as they possibly can, rather the imperative is to spend our lives and use our gifts in glorifying God and Enjoying Him forever.