The prohibition against wearing garments of mixed wool and linen, as stated in Deuteronomy 22:11 and Leviticus 19:19, highlights a principle of separation. This directive, known in Hebrew as sha'atnez, specifically refers to the combination of wool and linen together. God instructed the Israelites not to wear such mixed fabrics, emphasizing their distinct identity as a holy people chosen by Him. Under the New Covenant, while the physical act of mixing wool and linen may not be binding, the spiritual principle of separation remains vital. We are called to maintain spiritual purity, avoiding the sin that surrounds us, as we are a chosen generation and His own special people. There may also be practical benefits to avoiding such mixtures, as God's instructions often carry inherent wisdom, even if not mandatory today.

The prohibition on mixing wool and linen in Leviticus 19:19 and Deuteronomy 22:11 is a consumer protection law whose principle is that materials of widely differing character and texture are not to be combined. Clothing fibers fall into two basic kinds: plant cellulose fibers such as linen and cotton, and animal protein fibers such as wool and silk. Because these two kinds differ markedly in strength, washability, and absorption, they should not be mixed. Mixing within a kind is acceptable, so cotton with linen, or wool with mohair or silk, breaks no law because the fibers are basically similar. Synthetics such as Dacron, nylon, polyester, and rayon do not necessarily break the principle either, since they are made to share the characteristics of the natural fibers they are blended with. Fibers that are naturally or artificially compatible may be combined, and the principle concerns only fibers of markedly differing qualities. Mixtures usually yield a cheaper garment than the best pure fibers, though low-grade natural fabric is often improved by compatible man-made fibers. Clothing of lower quality or the wrong mixture need not be thrown away, and wearing it is not sin in itself. God does not want manufacturers to produce shoddy materials in order to take advantage of customers. Buy the best quality one can afford, to honor God in what one wears, especially for church services, but do not go into debt to do so.