Since the Reformation, Paul’s theology of the cross has been paramount. Since the early twentieth century, however, NT scholars have emphasized eschatology (to varying degrees “realized,” or not). 

Paul’s thought seems best encapsulated by understanding the two messianic comings as accomplishing disparate ends—Christ’s crucifixion sacrificially unto Christ’s Parousia gloriously, attaining the Jewish apocalyptic hope of eternal life (cf. Rom. 5:9; 1 Cor. 11:26; Phil. 3:11). Thus, Paul is not saying one main thing in his letters, but rather two main things. - John P. Harrigan