Philippians 3:2 warns us to beware of dogs.  What does that really mean?  Dr. P explains here.

Philippians 3:2 (KJV)

2 Beware of dogs, beware of evil workers, beware of the concision.

Proverbs 26:11

11 As a dog returneth to his vomit, so a fool returneth to his folly.

Matthew 5:28

28 But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.

Revelation 22:15

15 For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.

1 Peter 1:16

16 Because it is written, Be ye holy; for I am holy.

Deuteronomy 23:18

18 Thou shalt not bring the hire of a whore, or the price of a dog, into the house of theLord thy God for any vow: for even both these are abomination unto the Lord thy God.

Matthew 11:15

15 He that hath ears to hear, let him hear.