Tobias said:
Gen 24:
[64] And Rebekah lifted up her eyes, and when she saw Isaac, she alighted from the camel,
[65] and said to the servant, "Who is the man yonder, walking in the field to meet us?" The servant said, "It is my master." So she took her veil and covered herself.
[66] And the servant told Isaac all the things that he had done.
[67] Then Isaac brought her into the tent, and took Rebekah, and she became his wife; and he loved her. So Isaac was comforted after his mother's death.
Adam and Eve were not the only ones in th Bible to not have a wedding. I can't see any place here where Issac and Rebecca did either. Unless you are counting her going away party before she left home and before they even met each other?
You are quite right. There is no mention of a marriage ceremony or vows anywhere in the Bible, yet WRT Isaac and Rebecca, it does say, "she became his wife." WRT Judah and Tamar (Genesis 38), OTOH, it is very clear that she did not become his wife, although he did legitimate her sons.
IOW, the OT gives examples of many "family irregularities." These gnerally were regularized in some way. Some examples can be found in Genesis 12 and Genesis 20. In both of these, there was a question as to whose wife Sarah was. What is clear from these stories is the importance of her having only one husband, and something had to be done to clarify who her husband was.
What I see here is a variety of practices, but when there was an irregularity, something was done to clarify whether there was a marriage or not.
The Bible is quite vague on any set marrage rules. What is the difference between fornication and the act of marrage? I think the only determining factor we can get from the Bible is intent. If a couple intends their actions to be that of marrage, then God sees their hearts.
Read Genesis 12-38 and see whether the private intention of the two individuals alone seems to be enough. I don't think it is. Read Exodus 21, where the status of a wife, a daughter and a female slave are clarified.
Other places in the Law talk about the consent of a virgin's father being necessary for her to be married.
There is no biblical law saying it must be publicly declared before God recognizes it. There are no vows God requires.
You are correct that God does not require vows. You are also correct that the order in which the steps are taken is not all that important. However, it is also clear that there are some circumstances in which it might be unclear whether a couple is married or not, and in these situations, something is always done to clarify their status within the community. Therefore, I think one of the elements of marriage is that the community eventually recognizes the relationship as a marriage and not as some other kind of relationship such as slavery, prostitution, rape or adultery. The very concept of adultery presupposes marriage. Deuteronomy prescribes a method for making it clear that a marriage has ended, as well.
Couples who have chosen to live togeather without making it official run strait into problems with man's laws and traditions the minute they show up at a church looking for help. Many times instead of encouragement on how to work through their problems they are told that they are living in sin and must separate until they can have the ceremony man requires.
I agree such couples are often mistreated by churches. However, I also think it is biblical to find some way to clarify whether they are married or not. Forcing an immediate separation while this is being worked out is not necessary, IMHO. If they are living as a family, especially if they have children together, the church should not split them up, but should help them regularize their marriage so everyone will understand they are to be treated as a married couple.