A: In Christian tradition, Satan is the primary adversary (along with sin and death) of both God and humanity. The word Satan essentially means “accuser” or “adversary”. He is referred to by many names (Lucifer, Beelzebub, the Father of Lies, etc) but is most commonly called Satan or “The Devil”, the latter of which essentially means “slanderer”. While there exists a spectrum of belief regarding Satan, even in historic orthodox Christianity, he is most commonly considered to be the leader of all that is opposed to God and is associated with both the introduction of Sin into the human race and the ongoing temptation and accusation of humanity.
See also: Job 1:6-12, 2:1-5, 3:8, 41:1; Psalms 74:14, 104:26; Isaiah 14:12-15, 27:1; Zechariah 3:1-2; Mark 3:22-26; Luke 10:18, 22:31; John 12:31, 16:11; 1 Corinthians 5:5,13; 2 Corinthians 11:14; 1 Peter 5:9; Revelation 12:1-17