Do you ever indulge in the least obscenity? Some so-called Christians do, and it is sickening and disgusting to others; and while it shows what their thoughts dwell on, it does themselves great harm, for it keeps temptation before their minds, and makes it a great deal more difficult to resist temptations when they come in their lives. Do you mean it only as innocent fun? It is not innocent. For if you are so hardened as to unclean thoughts, that they don't hurt _you_, they, will hurt others.
What about swearing? If the devil can get you to swear a few times, then he will say: "Oh, you might as well confess that you are no Christian, and give up this hypocritical business." There is one of the Ten Commandments forbidding to take God's name in vain; the Sermon on the Mount forbids it still more strongly, and James, in chapter v., 12, condemns it in the strongest language. And yet there are some church members who practice it, especially when they get mad. That man's heart is not right, and he is treading on very dangerous ground who is not changed enough to avoid swearing. And if a man, by God's grace, will turn away from it and from the thought of it, he will soon become so that it will make him shudder to hear others swear. I know this from my own experience.
If you do not watch yourself in conversation, you will tell things that are not true; and so, in trying to be polite, you will have to watch or your tongue will tell a falsehood, and you will recollect it with shame and lose strength of faith in God.
And then that tongue often indulges in gossip about your acquaintances that does them great harm. And have you not, in moments of temper and passion, said cruel and, perhaps, false things to your dear ones; to those who have worked for you, and maybe would die for you? It cut them to the heart, and you have not made acknowledgment of your sin to them.
"A double-minded man is unstable in all his ways."