Proverbs 25:19-22 19 ¶ Confidence in an unfaithful man in time of trouble is like a broken tooth, and a foot out of joint. 20 ¶ As he that taketh away a garment in cold weather, and as vinegar upon nitre, so is he that singeth songs to an heavy heart. 21 ¶ If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink: 22 For thou shalt heap coals of fire upon his head, and the LORD shall reward thee.
4Ever:
Perhaps this verse may help you in dealing with your father-in-law. I know that enemies are normally those who want to harm us and we don't consider fellow believers as enemies. However, in this situation, your Dad appears to be walking in the flesh and is practically like an enemy as long as he continues this double standard. As such, you can follow the proverb's advice and essentially embarras him and bring him under the conviction of the Holy Ghost (Spirit).
I know that there is no surety that he will notice and repent his ways, however, your own actions can remain integral. He will have no place from which to attack you in legality as long as your own heart is right and you have fufilled the Law of God by loving. <img src="/forum/images/graemlins/argue.gif" alt="" /> I know it is so tempting to take offense, in the natural, you appear to have every justification to do so, but the above scriptural injunction is a good course of action. Who knows that he may take notice that your walk of faith is superior to the legalistic tight rope that he is on.