2:13 But. With this word Paul begins to assure his readers that he does not include them with those he has just mentioned in vv. 11 and 12, who refuse to love the truth and will fall prey to deception.
God chose you. See note 1 Thess. 1:4. From the beginning (Eph. 1:4), God chose them “through” sanctification and believing the truth, not “because of” these actions. According to Paul, the elect cannot continue to live in a godless fashion after they are converted.