Romans 9:1
1I tell the truth in Christ. I am not lying, my conscience testifying with me in the Holy Spirit
Paul’s oath in Christ, with the Spirit as witness, is not theatre. Wesley: In Christ—this seems to imply an appeal to him; in the Holy Ghost—through his grace. The man who will name Israel’s privileges and Israel’s unbelief starts by swearing he is not their enemy.
Wesley’s heirs hear a pastor of kinsmen, not a decree that has already discarded them. The truth he speaks will distinguish Israel within Israel (v. 6), but the distinction is not a cold list. Grief that needs an oath is grief for people who might still believe—and who, as 9:30–32 will say, still resist.
Calvin: as it was an opinion that Paul was a sworn enemy to his own nation, he adopts a preface and declares by an oath that he speaks the truth. The oath does not postpone election; it prepares the reader for a hard distinction inside Israel.
Conscience in the Holy Spirit is not a disclaimer of sovereignty. The next verses will name privileges and then deny that every Israelite is Israel. Sorrow under oath and a purpose of election (v. 11) will stand together, as they did in Calvin’s comment on v. 2.