While they behold For minds, however alienated from the true faith, are subdued, when they see the good conduct of believers; for as they understood not the doctrine of Christ, they form an estimate of it by our life. It cannot, then, be but that they will commend Christianity, which teaches purity and fear.

While they behold your chaste conversation - Your pure conduct. The word chaste here (ἁγνὴν hagnēn) refer's to purity of conduct in all respects, and not merely to chastity properly so called. It includes that, but it also embraces much more. The conduct of the wife is to be in all respects pure; and this is to be the grand instrumentality in the conversion of her husband. A wife may be strictly chaste, and yet there may be many other things in her conduct and temper which would mar the beauty of her piety, and prevent any happy influence on the mind of her husband,
Coupled with fear - The word fear, in this place, may refer either to the fear of God, or to a proper respect and reverence for their husbands, Ephesians 5:33. The trait of character which is referred to is that of proper respect and reverence in all the relations which she sustained, as opposed to a trifling and frivolous mind. Leighton suggests that the word fear here relates particularly to the other duty enjoined - that of chaste conversation - "fearing the least stain of chastity, or the very appearance of anything not suiting with it. It is a delicate, timorous grace, afraid of the least air, or shadow of anything that hath but a resemblance of wronging it, in carriage, or speech, or apparel."

Chaste conversation - with fear - While they see that ye join modesty, chastity, and the purest manners, to the fear of God. Or perhaps fear, φοβος, is taken, as in Ephesians 5:33, for the reverence due to the husband.

While they behold your chaste conversation,.... Cheerful subjection, strong affection, and inviolable attachment to them, and strict regard to the honour of the marriage state, and to the preserving of the bed undefiled with lusts and adulteries:
coupled with fear; with reverence of their husbands, giving them due honour, and showing all proper respect; or with the fear of God, which being before their eyes, and upon their hearts, engages them to such an agreeable conversation.

behold--on narrowly looking into it, literally, "having closely observed."
chaste--pure, spotless, free from all impurity.
fear--reverential, towards your husbands. Scrupulously pure, as opposed to the noisy, ambitious character of worldly women.

Joined with a loving fear of displeasing them.