The only conclusion to this viewpoint would be that abstinence is a valid form of birth control within marriage. This does not seem to line up with scripture.
1 Cor 7:1-5 is pretty frank regarding this matter...
"Now for the matters you wrote about: It is good for a man not to marry. But since there is so much immorality, each man should have his own wife, and each woman her own husband. The husband should fulfill his marital duty to his wife, and likewise the wife to her husband. The wife's body does not belong to her alone but also to her husband. In the same way, the husband's body does not belong to him alone but also to his wife. Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control. "
Some of you didn't know that stuff was in the Bible, did you?
Paul says that one purpose for marriage is to protect men and women from fornication. He explicitely states that abstinence is not to be long-term, and apparently only by agreement for a time of prayer. In marriage, couples are entirely free to satisfy each other. There is nothing unspiritual about sex between marriage partners... for any reason they desire.
The Old Testament guys had something to say on the matter, also...
"Drink water from your own cistern,
running water from your own well.
Should your springs overflow in the streets,
your streams of water in the public squares?
Let them be yours alone,
never to be shared with strangers.
May your fountain be blessed,
and may you rejoice in the wife of your youth.
A loving doe, a graceful deer—
may her breasts satisfy you always,
may you ever be captivated by her love."
"satisfy you always"... "captivated by her love"... Reads like a Valentine card (or a romance novel)... Pretty racy stuff... there's no question that there is an element of pleasure intended in the intimate monogamous relationship between a husband and wife.
So, abstaining from sex within a marriage relationship is not only a bad idea, it is disobedient to God's Word. The Bible commands Christian couples not to withhold from one another sexually.