It scares me when I meet people who profess to be believers, but they are engaging in extramarital or premarital sex and have rationalized it somehow. They say that God is cool with it. But God is not cool with it. It is a sin against Him.
When you are spiritually lethargic, you are more vulnerable to these sins. Case in point: King David. He was plucked from obscurity as a shepherd boy to become a giant killer in the valley of Elah and later the great king of Israel. He was a wonderful, powerful, and godly man. But after years of walking with the Lord, David put his spiritual life on cruise control, and we read that "late one afternoon, after his midday rest, David got out of bed and was walking on the roof of the palace. As he looked out over the city, he noticed a woman of unusual beauty taking a bath" (2 Samuel 11:2). That woman, by the way, was Bathsheba.
Interestingly, this was the time when wars were being fought. David's troops were out on the battlefield, and David, the warrior-king, should have been leading them as he always did. Instead, he was kicking back. He was taking some time off. But you don't feed lust—you starve it. The moment you back off in the spiritual battle, you will be vulnerable. The moment you fall asleep, you will be weak. You can't take a spiritual vacation.
That is why Paul wrote to Timothy, "Run from anything that stimulates youthful lusts. Instead, pursue righteous living, faithfulness, love, and peace. Enjoy the companionship of those who call on the Lord with pure hearts" (2 Timothy 2:22).
This is the warning: Stay away from those things. Stay away from anything that would encourage immoral living.