Is dancing a sin?
Answer: In order for sin to exist, there must be law (Rom. 5: 13). Sin is lawlessness or the breaking of God's law (1 John 3: 4). Is dancing, then, in conflict with the law of Christ, the perfect law of liberty (Gal. 6: 2, Jas. 1: 25)?
There are two kinds of dance recognized in the Bible. One type of dance recorded in the Bible was a dance that involved the expression of joy in worship to God (Ps. 150: 4). David "danced before the Lord" (2 Sam. 6: 14). This is the same type dance that was performed when the prodigal son returned (Luke 15: 25). It is important to notice that the dance here mentioned was male and female segregated. One work states, "Women seem generally to have danced by themselves, one often leading the rest" (ISBE, Vol. 2, pg. 1170).

The New Testament does not teach dance as an act of worship today, I might add. The other dance is that kind of dance that was designed to stimulate the lust of the flesh (Ex. 32). This dance seemed to involve both men and women together and was performed in a spiritually opposed climate (Ibid.). Herodias' daughter also performed a sensual dance that was probably more of Roman origin and influence (Matt. 14: 6).
The modern dance. The modern dance, as a rule, is certainly not performed out of joy and worship. The drinking of alcohol, petting, and adultery are often the companions of the secular dance. Lasciviousness (aselgeia) is a biblical word used to describe and condemn wantonness and unbridled lusts (1 Pet. 4: 3). The secular dance usually involves the male and female in improper physical contact..

 Consider Henry Thayer's comments on lasciviousness: "...indecent bodily movement, unchaste handling of males and females" (Greek-English Lexicon, pg. 79, 80). Hence, lasciviousness vividly describes the secular dance.
In short, the modern dance is a prelude to fornication and adultery. The dance comes under the heading of "the works of the flesh" (Gal. 5: 19, cp. 1 John 2: 15-17).