WGN Salem is heavily inspired by history and in particular by the folklore, superstitions and literature of both Europe and North America. The Bible was also another source of inspiration. The themes featured throughout the series are highlighted by carefully chosen episode titles.
The Beckoning Fair One is a reference to the regained beauty of Mercy Lewis as well as a literary reference to the novella The Beckoning Fair One by Oliver Onions, widely regarded as one of the best in the genre of horror fiction, especially psychological horror. 
This novella is included in Widdershins (1911), whose name inspired some characters on Salem.
2.08 Dead Birds
The death of birds is an omen of misfortune. For millennia witches and priests have used birds for divination purposes. 
John Sibley hid a litter of dead crows in his beds and flocks of crows died in front of his window.
2.09 Wages of Sin
From the Bible verse Romans 6:23 “For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.” as mentioned by Brannon Braga in the Writer's Wrap. 
Whilst waiting the Raising of Satan, the characters are being accounted for their sins.
2.10 Til Death Do Us Part
A phrase from the marriage liturgy in the Book of Common Prayer. It refers to Anne and Cotton's wedding, but also the preparation of the dreadful Grand Rite. And only Mary's death can prevent the Devil to become flesh and blood.
2.11 On Earth as in Hell
We are at the final chapters and the flames of Hell began to claim more victims. Nothing is as it was, especially for Mary Sibley who has lost everything.
Colloquially, it refers to midnight but in this particular case, it refers to the fateful hour when the Devil came to Earth to bring the defeat of humankind, including even his most faithful witches. 
3.01 After the Fall
After the Fall is a free reference to Arthur Miller, author of The Crucible. This idiom often refers to the fall of humanity tempted by the Devil to sin against God. Even Lucifer once fell — literally or figuratively — when he was cast out of Heaven. 
3.02 The Heart Is A Devil
Love is a strong feeling that leads to pleasure, but also to evil and temptation. In Salem, this is quite literal. 
3.03 The Reckoning
The Reckoning refers to the ritual of the same name used to deprive witches of their powers as punishment. The ritual is a showdown in all respects.
3.04 Night's Black Agents
The title designates witches hired by the Devil to do his bidding.
It is a reference to one of Adam Simon's favourite quotes, taken from Shakespeare's Macbeth, Act III, Scene II: “"Good things of day begin to droop and drowse; Whiles night’s black agents to their preys do rouse."” 
3.05 The Commonwealth of Hell / The Witch Is Back
Commonwealth refers to the greater good. For the evil ones.
Witch is Back in reference to the return of the Countess Von Marburg.
The last words uttered by Mary at the end of the episode are a clear statement that marks the return of Mary Sibley as she once was.
3.06 Wednesday's Child
Wednesday refers to the day of the week the events are taking place. Moreover, it is a clear reference to the eerie nursery rhyme, the "Poetry of the Devil."