When we make light of sin ("But a little [insert sin type here] won't hurt..."), we make light of Satan. Jude 9 says, " But Michael the archangel, when he disputed with the devil and argued about the body of Moses, did not dare pronounce against him a railing judgment, but said, “The Lord rebuke you!”
Satan's a powerful, supernatural evil. Take sin, and thus Satan, seriously and with a sober mind.
"For the entire Law is fulfilled in in this one word: "You shall love your neighbor as yourself."—Gal 5:14