Not a few people, and even many Christians, think that the Bible contains some strange laws. For instance, Deuteronomy 22:11 forbids the wearing of a garment that contains different fabrics. Mike Ford tackles this particular command, contending that it contains a spiritual principle with a profound impact on Christian life.
Mike Ford explores the possible physical and spiritual significance of the prohibition to mix wool and linen which appears in Deuteronomy 22:11 and Leviticus 19:19. One explanation seems to come from the consumer protection corner, asserting that mixing fibers produces an inferior garment. Some commentaries refer to the respective offerings of Cain and Abel, suggesting that linen may represent worldliness or unrighteousness (even though the book of Revelation tells us the saints will be clothed in linen), while wool symbolizes righteousness. Some Protestant commentaries jump to the conclusion that linen refers to works while wool refers to grace, indicating that they should never be joined. Some commentaries suggest that linen signifies Egypt (even though the Aaronic priests were commanded to wear linen undergarments) and that Israelites were forbidden to mix with Egypt. Realizing that since neither one jot nor tittle will pass from the Law until heaven and earth pass away, we are obligated to look for the commonsense spiritual applications. Since this law appears with other prohibitions of mixing seed, mixing livestock, and keeping things separate, we conclude that God wants us to remain separate from the world, not being unequally yoked with any aspect of this world.
John Ritenbaugh reiterates that the entire Old Testament was written with the New Testament church in mind. Certain temporary ceremonial sacrifices, washings, and rituals were set aside when the spiritual reality—such as Christ's sacrifice replacing animal sacrifices and God's Holy Spirit and His Word replacing physical washings (Hebrews 9:18; Ephesians 5:26)—added a spiritual dimension. All biblical law, including the ceremonies, comes from God. Paul never taught any Jew to forsake the Law of Moses, the constitution and civil code, but he did rail against Pharisaical additions for the expressed purpose of attaining justification. Even though a change occurred in the administration of existing law, no laws were done away. Instead, they are written in the hearts of the converted (Hebrews 8:10; 10:16).