cast them into the pit
This phrase is unique in the New Testament and borrows from the pagan Greek concept of casting someone into Tartarus, a place of divine punishment (cf. BDAG on ταρταρόω). Technically, unbelievers are not cast into hell until the end in Revelation 20, where they are cast into the lake of fire. Right now, the place of punishment for unbelievers is the abyss or pit (cf. Job 33:22, 28; Pss 30:3; 94:13; Rev 9:1, 2).

being kept
The phrase “being kept” translates the participle τηρουμένους (tēroumenous) from τηρέω (tēreō). Peter used the same term in 1 Peter 1:4 to talk about the believers’ inheritance “being kept” by God in heaven for them. This then contrasts with 2 Peter, where Peter emphasizes that false teachers, unbelievers, and the present world are “being kept” for a day of judgment by God (cf. 2 Pet 2:9, 17; 3:7).

suffering unrighteousness
The phrase, “suffering unrighteousness” translates the Greek participle ἀδικούμενοι (adikoumenoi). The rendering with “unrighteous” rather than something like “wrong” preserves consistency for the term. This consistency helps to show how the false teaches are repaid exactly according to their deeds. They suffer unrighteousness in return for their unrighteousness. This translation also brings out the connection to Balaam as an example of a worker of unrighteousness receiving what he earned (2:15).

considering…—they are stains and blemishes
The translation here and in verse 14 with a dash followed by a conclusion about the false teachers helps to bring out the parallel structure Peter employs in these two verses. In each case he uses a participial phrase, following it with an adjectival phrase which describes the false teachers. By using a parallel structure like this, Peter highlights negative aspects of these men from two different angles. This verse describes their personal wickedness, identifying them as are stains and blemishes. Verse 14 describes their interpersonal wickedness which corrupts God’s family, meaning that they are accursed children. Maintaining a parallel translation for this parallel structure in Greek helps to bring this out more clearly in English.

having…—they are accursed children
Refer to the discussion on verse 13 above.

speaking out
The term rendered “speaking out” (φθέγγομαι; phthengomai) is used both here and later in 2:18. Peter intentionally uses the same term in connection to the false teachers by first showing how a donkey “spoke out” against Balaam, an unrighteous prophet for hire, while the false teachers here “speak out” arrogance and vanity. Peter, a faithful mouthpiece of the Lord, is in a sense speaking out against false teachers and that which they speak out—a characteristic of any faithful prophet and mouthpiece of the Lord, even, as in the case of Balaam, when that mouthpiece is a donkey.

speaking out
Refer to the discussion on verse 16 above.

For if they are overcome
This translation fronts the clause’s main verb “overcome” (ἡττάομαι; hēttaomai) which is modified by the two participles “having escaped” (ἀποφεύγω; apopheugō) and “having been entangled” (ἐμπλέκω; emplekō) to help readers more easily see the emphasis Peter is placing on the false teachers. Although these false teachers promise freedom, even they do not have it, but are enslaved to their sins which overcome them (cf. 2:19). Peter emphasizes this domination of sin over them by placing “they are overcome” at the beginning of the sentence. This also shows the close connection between this verse and the previous, where Peter states the principle that a man is enslaved by what he is overcome. This is then applied directly to the false teachers in the present verse.