{Knowing} (eidotes). Second perfect active participle of
oida (eidon), a so-called causal participle=since we know,
the third participle with the principal verb eucharistoumen,
the Greek being fond of the circumstantial participle and
lengthening sentences thereby (Robertson, _Grammar_, P. 1128).
{Beloved by God} ((8867)ap(886d)enoi hupo [tou] theou). Perfect passive
participle of agapa(935c), the verb so common in the N.T. for the
highest kind of love. Paul is not content with the use of
adelphoi here (often in this Epistle as  2:1,14,17  3:7  4:1,10 ), but adds this affectionate phrase nowhere else in the
N.T. in this form (cf.  Jude 1:3 ) though in Sirach 45:1 and on
the Rosetta Stone. But in  2Th 2:13  he quotes "beloved by the
Lord" from  De 33:12 . The use of adelphoi for members of the
same brotherhood can be derived from the Jewish custom ( Ac
2:29,37 ) and the habit of Jesus ( Mt 12:48 ) and is amply
illustrated in the papyri for burial clubs and other orders and
guilds (Moulton and Milligan's _Vocabulary_). {Your election}
(	(886e) eklog(886e) hum(936e)). That is the election of you by God. It is
an old word from eklegomai used by Jesus of his choice of the
twelve disciples ( Joh 15:16 ) and by Paul of God's eternal
selection ( Eph 1:4 ). The word eklog(885c) is not in the LXX and
only seven times in the N.T. and always of God's choice of men
( Ac 9:15  1Th 1:4  Ro 9:11  11:5,7,58  2Pe 1:10 ). The divine
eklog(885c) was manifested in the Christian qualities of verse  3 
(Moffatt).