Holiness is essentially an inward thing, and we all know that the state of our hearts is of paramount importance, but nevertheless outward matters are also affected.
It has been quoted that man looks on the outward, but God looks on the heart, but if we looked a little more closely at that quotation in its original context we would find that it is not about clothes. The prophet Samuel used it when he was about to choose Israel's king. Jesse's sons were brought before him and Samuel was convinced that Eliab would be the one, but the Lord said, "Look not on his countenance (his good looks) or on the height of his stature (his physique)... for the Lord seeth not as man seeth, but looketh on the heart". (1 Sam. 16:7).
Dress and comportment are brought to our attention in the first epistle of Peter chapter three, and what has surprised the writer, is that in all the new developments in the life of the Church during recent times little or nothing has been said about the dress of the Christian, male or female. It all seems to be do-as-you-please.