Is it a sin to use birth control, or to have marital relations with your wife without the intentions of having a baby? 

Thank you for your question, and your evident desire to obey the Lord in even personal matters of life. 

To answer your question, the short answer is no.  There is no Scripture that says it is a sin to use birth control, nor does it state that having marital relations with your wife becomes a sin if you do not necessarily intend to have a baby nine months later, although Genesis 38:6-10 gives a very specific case in which God disapproved of one form of this action.  We'll say more about this passage later in this article. 

Now let's explore this issue a little.  The teaching of Scripture is clear that the physical act of marriage is intended by God. 

"Now concerning the things whereof ye wrote unto me: It is good for a man not to touch a woman.  Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.  Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband.  The wife hath not power of her own body, but the husband: and likewise also the husband hath not power of his own body, but the wife.  Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again, that Satan tempt you not for your incontinency."  1Corinthians 7:1-5

Now whether children are formed from this union is a blessing that God controls.  Here are a few verses about this:

"And the LORD visited Sarah as he had said, and the LORD did unto Sarah as he had spoken."  Genesis 21:1

"And they rose up in the morning early, and worshipped before the LORD, and returned, and came to their house to Ramah: and Elkanah knew Hannah his wife; and the LORD remembered her."  1 Samuel 1:19

"And the LORD visited Hannah, so that she conceived, and bare three sons and two daughters.  And the child Samuel grew before the LORD."  1 Samuel 2:21

"As thou knowest not what is the way of the spirit, nor how the bones do grow in the womb of her that is with child: even so thou knowest not the works of God who maketh all."  Ecclesiastes 11:5

However, two things make this issue more complex than the short answer above would seem to indicate.  First, it is becoming increasingly well-known that many modern, popular forms of birth control occasionally fail in their primary purpose which is to prevent fertilization of an ovum (or egg) by sperm.  When this first purpose fails, there is often a secondary effect that strongly hinders an already fertilized egg from attaching to the womb to receive the nourishment it needs to continue to develop and grow. 

If a new life begins at the moment that an ovum is fertilized, then that life is ended by the effects of many so called birth-control methods.  For more information on this topics see the booklet entitled Does the Birth Control Pill Cause Abortions?  by Randy Alcorn or go to www.prolife.com/BIRTHCNT.html

However, we should be uncomfortable basing our decisions solely on the claims of medical science.  We should note that in the Bible the steps in the process went something like this:

A man "knew" his wife She "conceived;" sometimes it even says the Lord "visited" to grant the couple conception.  She is described as "with child"

If the Bible says it's a child, it is wrong to end its life.  Furthermore, if God visited in order to give conception, surely it's contradicting Him to end the process He had just begun.  So any form of "birth-control" that ends a life is clearly wrong. 

The second complexity that should be mentioned is the issue of whether we should try to limit family size at all, even if it's never directly called a sin to do so.  The most popular way of thinking about this today seems to be that a couple should have only as many children as they feel they can be responsible for or provide for.  Therefore, many, if not most, couples have only one, two or three children, so they can obey God's command to provide for their children.  On the other hand, many who try to follow God's word feel that if they do nothing to hinder pregnancy, they are leaving in God's hands how many children they have.  If anyone thinks they have more than they can provide for, then they must be incorrect because God chose to give them that many, and He will not give you more than you can handle. 

The Bible never even implies that having too many children is irresponsible, not does it ever actually say having too few children is a way of directly disobeying Him.  However, it does say children are a blessing. 

"Lo, children are an heritage of the LORD: and the fruit of the womb is his reward.  As arrows are in the hand of a mighty man; so are children of the youth.  Happy is the man that hath his quiver full of them: they shall not be ashamed, but they shall speak with the enemies in the gate."  Psalms 127:3-5

And when one man refused to father children because they would be considered the children of his deceased brother, it displeased God so much God killed him for it. 

"And Judah took a wife for Er his firstborn, whose name was Tamar.  And Er, Judah's firstborn, was wicked in the sight of the LORD; and the LORD slew him.  And Judah said unto Onan, Go in unto thy brother's wife, and marry her, and raise up seed to thy brother.  And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother's wife, that he spilled it on the ground, lest that he should give seed to his brother.  And the thing which he did displeased the LORD: wherefore he slew him also."  Genesis 38:6-10

So the implication of scripture often contradicts the purposeful limiting of family size. 

On the other hand, the following scriptures indicate there are unusual times when having children is not a blessing:

"Sing, O barren, thou that didst not bear; break forth into singing, and cry aloud, thou that didst not travail with child: for more are the children of the desolate than the children of the married wife, saith the LORD."  Isaiah 54:1

Here it is the desolate (not the blessed) who have the children. 

"But woe unto them that are with child, and to them that give suck, in those days!  for there shall be great distress in the land, and wrath upon this people."  Luke 21:23

Here is a woe (certainly not a blessing) pronounced on women with children, both unborn and infants, in the troubled end-times in Judaea. 

"Now concerning virgins I have no commandment of the Lord: yet I give my judgment, as one that hath obtained mercy of the Lord to be faithful.  I suppose therefore that this is good for the present distress, I say, that it is good for a man so to be."  1 Corinthians 7:25-26

Here is Paul recommending (not commanding) virgins to refrain from marriage (and by implication from having children) in a time and place of distress in the church age. 

Please note there are no such warnings about having many children for the popular modern reasons of obtaining a richer, more luxurious, fun or convenient lifestyle.  Not having children for these reasons surely indicates a preference for the rewards of the world over the reward of God which is directly stated to be "the fruit of the womb."  The heart motive is key. 

There are many issues in the Bible that God gave a direct statement about, sometimes forbidding that a thing be done, and sometimes commanding that a thing must be done.  Since this issue is not dealt with quite so clearly as that, most Bible-Believers consider it a doubtful thing, and apply Paul's rules for doubtful things from Romans 14:5-6 , 22. 

"Let every man be fully persuaded in his own mind" Do what you do "as unto the Lord" "Happy is the man that condemeth not himself in that thing which he alloweth"

Probably the best way to study this issue for yourself is to look up the occurrences of the words "conceive", "conceived", and "with child" in the Bible.  Then you can base the decision you and your family will make on your understanding of what God says about this issue in His Holy Bible.