To separate us (ημας χωρισα). Aorist active infinitive of χοριζω (same verb as in Romans 8:35). God's love is victor over all possible foes, "God's love that is in Christ Jesus." Paul has reached the mountain top. He has really completed his great argument concerning the God-kind of righteousness save for its bearing on some special problems. The first of these concerns the fact that the Jews (God's chosen people) have so largely rejected the gospel (chapters Romans 8:9-11).

Romans 9:1

In Christ (εν Χριστω). Paul really takes a triple oath here so strongly is he stirred. He makes a positive affirmation in Christ, a negative one (not lying), the appeal to his conscience as co-witness (συνμαρτυρουσης, genitive absolute as in Romans 2:15 which see) "in the Holy Spirit."