A.T. Robertson Commentary 1 Thessalonians 3:13

"to the end he may establish your hearts unblameable in holiness before our God and Father, at the coming of our Lord Jesus with all his saints." — 1 Thessalonians 3:13 (ASV)

To the end he may stablish (εις το στηριξα). Another example of εις and the articular infinitive of purpose. Same idiom in 3:2. From στηριζω, from στηριγξ, a support.

Unblameable (αμεμπτους). Old compound adjective (α privative and verbal of μεμφομα, to blame). Rare in N.T. Predicate position here. Second coming of Christ again.