According to Catholic teaching that is biblically supported, who are "the enemies of Christians?" From Luke 1:68-79 (RSVCE), Catholics have a prayer that is termed CANTICLE OF ZECHARIAH (the Benedictus [cf. Traditional Prayers — Common Prayers | liturgyoffice.org.uk]). In it there is a section:


  [...]
  
  Through his holy prophets he promised of old that he would save us
  from our enemies, from the hands of all who hate us. He promised to
  show mercy to our fathers and to remember his holy covenant.
  
  This was the oath he swore to our father Abraham: to set us free from
  the hands of our enemies,
  
  [...]


From Catholic teaching that is biblically supported, who are these enemies of Christians because obviously applying this passage to Christians, the traditional enemies of Israel - like the nations they battled - may most likely not apply to Christians.
Regarding the promise to Abraham:

Christians consider themselves to be the (spiritual) descendants of Abraham, certainly as it applies to inheriting the promises of God to Abraham. This is based on passages such as Matthew 3:9, Luke 3:8, Romans 9, and Galations 3:7. Therefore the passage you quote is taken to mean that God promises to protect Christians from their enemies.

Regarding Enemies

As for the interpretation of the word 'enemies', there appears to be no reason not to take this word in its straightforward meaning - i.e. those who are opposed to you and would do you harm. That's almost certainly how it was intended in the original. There is nothing inconsistent with Christians having enemies - how could we be commanded to 'love your enemies' if we didn't have them? Note that the prayer does not ask for evil or punishment to be done to those enemies, but only that Christians are protected from them.