Romans 8:16

8:16 The Spirit himself bears witness to our spirit that we are God’s children.

Romans 9:10

9:10 Not only that, but when Rebekah had conceived children by one man, our ancestor Isaac –

tn Or possibly “with.” ExSyn 160-61, however, notes the following: “At issue, grammatically, is whether the Spirit testifies alongside of our spirit (dat. of association), or whether he testifies to our spirit (indirect object) that we are God’s children. If the former, the one receiving this testimony is unstated (is it God? or believers?). If the latter, the believer receives the testimony and hence is assured of salvation via the inner witness of the Spirit. The first view has the advantage of a σύν- (sun-) prefixed verb, which might be expected to take an accompanying dat. of association (and is supported by NEB, JB, etc.). But there are three reasons why πνεύματι (pneumati) should not be taken as association: (1) Grammatically, a dat. with a σύν- prefixed verb does not necessarily indicate association. This, of course, does not preclude such here, but this fact at least opens up the alternatives in this text. (2) Lexically, though συμμαρτυρέω (summarturew) originally bore an associative idea, it developed in the direction of merely intensifying μαρτυρέω (marturew). This is surely the case in the only other NT text with a dat. (Rom 9:1). (3) Contextually, a dat. of association does not seem to support Paul’s argument: ‘What standing has our spirit in this matter? Of itself it surely has no right at all to testify to our being sons of God’ [C. E. B. Cranfield, Romans [ICC], 1:403]. In sum, Rom 8:16 seems to be secure as a text in which the believer’s assurance of salvation is based on the inner witness of the Spirit. The implications of this for one’s soteriology are profound: The objective data, as helpful as they are, cannot by themselves provide assurance of salvation; the believer also needs (and receives) an existential, ongoing encounter with God’s Spirit in order to gain that familial comfort.”

tn Or possibly “by one act of sexual intercourse.” See D. Moo, Romans (NICNT), 579.