The Chinese philosophy of Ying (Yin) and Yang is becoming more prevalent in our culture.  You see people openly talking about their practice of it.  You hear others describe reasons for wearing jewelry (necklaces) that depict Ying & Yang.  People say they like the design - it's "cool."

As with anything, the Christian must form an opinion about this topic.  There is no shortage of information on the subject (books, internet, etc.).  Of course, our opinion must be grounded in the Bible.

Basically, the philosophy is about the origin of life and matter, and how man achieves the "perfect balance" between forces at work in the world.  Ying is responsible for the moon, femaleness, cold, and darkness.  Yang is liable for the sun, maleness, heat, and light.  The powers behind all this make for a balance in all universal matter so that at no time does one force continually dominate the other.  All phenomena can be understood using the principles of Ying & Yang.  This includes the movement of the stars, the workings of the body, ethical qualities of humans, the operations of governments, and even the nature of historical change.

 So what do you make of all this?  It seems to me to be nothing other than blatant idolatry.  It is a way of thinking that does not give God His proper credit as the Source of all life and as the Power behind all the workings of man.  Passages like Gen 1:1; Dan. 4:17,25; and Acts 17:24-28 would certainly argue against the foolishness of Ying and Yang.  The one who lives by every word that proceeds out of the mouth of God knows not to put any trust in such vain speculations of human wisdom.  God has always wanted us to seek Him out for the answers to our questions.  Balance will only be achieved when we realize that God's will is the only mindset that logically explains how everything is to work together (cp. Mt. 6:25-34).

Can a Christian practice Ying & Yang?  Obviously not.  Can a Christian even wear a "cool" necklace depicting it?  I would say not (cp. 1 Thess 5:22).  If you want "balance," live like God teaches you in His word.  If you want to wear something "cool," adorn the doctrine of Christ and throw Ying & Yang where it belongs - in the trash.