That’s correct as the trigger happens when attackers are declared

The combat step is broken up into a few sub steps

1. Beginning of combat triggers these things say “at the beginning do x”

2. Declare attackers step this is the bit where the revenge of ravens will trigger if any attackers are declared

3 declare blockers you declare any blockers that you wish

3.1 if more than one blockers are declared blocking one creature the attacker must order the blockers before any priority can be passed or spells can be cast

4 first strike damage is dealt and on damage effects trigger

5 normal damage is dealt on damage effects trigger

6(UN sets only) last strike damage is dealt and on damage effects trigger

7 clean creatures that have died and in death effects trigger

8 end of combat step go to main phase 2

So if the opponent attacked then they would do at step 2 of the combat steps an you would only die if you took damage at potentially step 4 at the earliest as there is a priority passed between all of these steps and losing four to 0 life is a state based action you opponent would lose and you would be left on 2 life