Dictionary
Blasphemy
In the sense of speaking evil of God this word is found in Ps. 74:18; Isa. 52:5; Rom. 2:24; Rev. 13:1, 6; 16:9, 11, 21. It denotes also any kind of calumny, or evil-speaking, or abuse (1 Kings 21:10; Acts 13:45; 18:6, etc.). Our Lord was accused of blasphemy when he claimed to be the Son of God (Matt. 26:65; comp. Matt. 9:3; Mark 2:7). They who deny his Messiahship blaspheme Jesus (Luke 22:65; John 10:36). Blasphemy against the Holy Ghost (Matt. 12:31, 32; Mark 3:28, 29; Luke 12:10) is regarded by some as a continued and obstinate rejection of the gospel, and hence is an unpardonable sin, simply because as long as a sinner remains in unbelief he voluntarily excludes himself from pardon. Others regard the expression as designating the sin of attributing to the power of Satan those miracles which Christ performed, or generally those works which are the result of the Spirit's agency.
Dictionary
Familiar spirit
Sorcerers or necormancers, who professed to call up the dead to answer questions, were said to have a "familiar spirit" (Deut. 18:11; 2 Kings 21:6; 2 Chr. 33:6; Lev. 19:31; 20:6; Isa. 8:19; 29:4). Such a person was called by the Hebrews an 'ob, which properly means a leathern bottle; for sorcerers were regarded as vessels containing the inspiring demon. This Hebrew word was equivalent to the pytho of the Greeks, and was used to denote both the person and the spirit which possessed him (Lev. 20:27; 1 Sam. 28:8; comp. Acts 16:16). The word "familiar" is from the Latin familiaris, meaning a "household servant," and was intended to express the idea that sorcerers had spirits as their servants ready to obey their commands.