Into the abyss (eis tēn abusson). See note on Luk 8:31 for this old Greek word (a privative and bussos) bottomless like sea (Psa 106:26), our abyss. In Rev 9:1 it is the place of torment. Paul seems to refer to Hades or Sheol (Act 2:27, Act 2:31), the other world to which Christ went after death.
To bring Christ up (Christon anagagein). Second aorist active infinitive of anagō and dependent on katabēsetai (shall descend). Christ has already risen from the dead. The deity and resurrection of Christ are precisely the two chief points of attack today on the part of sceptics.