Can a Christian place his hand on the Bible and swear an oath of any kind? Or, raise his right hand and swear to tell the truth, in a court room? Or, can a Christian swear, anywhere, anytime, under any circumstances? I find a difference in the word 'affirm' and the word 'swear.' What saith the Scriptures? I find people on both sides of this question, but I'm not able to find authority in the Scriptures for one to do so. I find where, if I understand it correctly, it is not to be done. A waiting your answer from the Scriptures. Can the answers come without using the Hebrew, or Greek language?
A study in Hebrew or Greek is certainly not necessary for this topic. What we see today as taking an oath is exactly what was being said in the Bible about taking an oath. Here are some passages that I think show a broad range of the its uses and questions.
Matthew 5:33-37. "Again, you have heard that it was said to the people long ago, 'Do not break your oath, but keep the oaths you have made to the Lord.' But I tell you, Do not swear at all: either by heaven, for it is God's throne; or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. And do not swear by your head, for you cannot make even one hair white or black. Simply let your 'Yes' be 'Yes,' and your 'No,' 'No'; anything beyond this comes from the evil one."
Matthew 23:16-23 "Woe to you, blind guides! You say, 'If anyone swears by the temple, it means nothing; but if anyone swears by the gold of the temple, he is bound by his oath.' You blind fools! Which is greater: the gold, or the temple that makes the gold sacred? You also say, 'If anyone swears by the altar, it means nothing; but if anyone swears by the gift on it, he is bound by his oath.' You blind men! Which is greater: the gift, or the altar that makes the gift sacred? Therefore, he who swears by the altar swears by it and by everything on it. And he who swears by the temple swears by it and by the one who dwells in it. And he who swears by heaven swears by God's throne and by the one who sits on it."
James 5:12 "Above all, my brothers, do not swear—not by heaven or by earth or by anything else. Let your "Yes" be yes, and your "No," no, or you will be condemned."
Hebrews 6:16 "Men swear by someone greater than themselves, and the oath confirms what is said and puts an end to all argument."
Numbers 30:2 "When a man makes a vow to the LORD or takes an oath to obligate himself by a pledge, he must not break his word but must do everything he said."
Leviticus 5:4 "Or if a person thoughtlessly takes an oath to do anything, whether good or evil—in any matter one might carelessly swear about—even though he is unaware of it, in any case when he learns of it he will be guilty."
Joshua 2:20 "But if you tell what we are doing, we will be released from the oath you made us swear."
In general, the taking of oaths is talked about negatively by Jesus and James. However, God swore oaths, God's people swore oaths, and Moses' Law legislated oaths. That would seem to indicate that there is more to the issue than a simple blanket prohibition. When I think about oath taking, I think of two basic types. One is the oath where a person is affirming before God on what they will do. They are vowing to complete an action. This is what most people do when they are married -- they vow to one another and before God to be husband and wife. The other type of oath is where someone is calling on a power higher than themselves to testify with them that they are telling the truth. Now I have personally known people who were ready to swear an oath at the least provocation. "I swear on a stack of Bibles that so-in-so is true." It isn't too hard to figure out that such a person is generally a liar and feels compelled to try to improve their credibility by swearing on something more important than themselves. However, people who have a reputation for honesty do not have to swear to affirm that they are telling the truth.
In Matthew 23, Jesus describes the folly of how the Jews of his day swore oaths. It sounds like they had created a complex system to determine when an oath was binding. Sometimes it was binding and sometimes it was not. Of course any such system is foolish and Jesus condemns the hypocrisy. By itself, that would not condemn all swearing of oaths, but it would condemn taking of oaths and then trying to get out of it. I think he is trying to tell the people to get out of the habit of swearing oaths for every trivial thing and build up a reputation of a person who keeps his word. Matthew 5 carries it a little further and adds a complete prohibition on trying to get holy objects into your swearing. Jesus concludes with the simple conclusion that you don't have the power to even change your hair color, so what good would it do to swear by things that belong to God?
I do not believe Jesus was talking about taking an oath for a solemn occasion such as a wedding or the taking of an oath of office. It is still "swearing", but it is in the context of a vow. Some of the brethren in Jerusalem were talking to Paul in Acts 21:23 "We have four men who have taken a vow." They wanted Paul to help them finish the ceremony to complete vows. Paul did not object and was even willing to pay for their expenses. That would show that since Paul did not condemn the action, but was going to participate in it, that it was not the sort of thing that Jesus had condemned.
I personally have wondered why people want to swear on a Bible. The part of an oath that is important is the "so help me God." I see the introduction of a Bible into the act of taking a vow as being worthless at best and a possible violation of what Jesus and James had said. At the same time, I see no practical difference in starting an oath by "I swear" versus "I affirm" when both statements end with "so help me God." It is the introduction of God into the statement that makes it an oath and not words leading up to it. Again, I will go back to traditional wedding vows. Most of those are worded in such a way so that neither "swear" nor "affirm" occur anywhere in the vow. Yet, most are still a solemn promise -- witnessed by God or before God, depending on the specific wording.
Making a vow should never be entered into lightly. It is before God and you are expected to fulfill it.