Leviticus says that priest should not marry divorced women (Lev.21.7). Perhaps this means that believers should not marry divorcees, because we are called a royal priesthood (1Peter.2.5). Although the literal laws about priests no longer apply to us, don't they still indicate God's general will for us?
Reply: This is a very interesting suggestion, but if we look at it more carefully, it leads to an absurd and contradictory conclusion. I agree that we are like priests, and that we should strive to be as holy as possible. That principle would imply that we should follow the more stringent rules laid down for High Priests in the old Temple and for all priests in the New Temple, who may not marry a woman who is divorced or widowed (Lev.21.13f; Ezek.44.22). So, if we follow this principle to its conclusion, believers should not marry widows, and yet Timothy is told to encourage Christian widows to marry (1 Tim.5.14).
Therefore it is better to regard the prohibition of priests marrying divorcees and widows as part of the symbolism of separation and purity, which is also seen in the clothes they wear, the way they cut their hair (Lev.20.5), the fact that they eat the edible parts of offerings, the way they serve in the Temple etc. They are set apart as different, holy, and separate, just as God is set apart, separate, and distant. But Jesus' death split the curtain and removed the barrier, bringing man and God together. There is no longer a separate priesthood because we are all priests, and there are no longer various stages of holiness between us and God because the Holy Spirit lives in all believers.
We are all priests, but we do not eat different food, or wear different clothes, or have different marriage regulations. The point about us ALL being priests is that these distinctions all disappeared when Christ broke all barriers down.
For Christians one type of food is no less holy than any other, and a divorcee is no less holy than someone who has never been married.
For more on our use of the Old Testament see The Church Can’t Do Without It in Divorce and Remarriage in the Church