How much life can I gain attacking someone who can't fall under 1 hp with lifelink creatures?
The damage is still dealt fully, even though Worship makes it so your life total can't go under 1. This means you gain the full 4 life from the lifelink creature.

Source: Gatherer rulings


  10/4/2004 It reduces your life total to 1, not the damage to 1.
  10/4/2004 Worship does not prevent damage. It causes some damage to be
  unable to lower your life total. So any damage rendered useless by
  Worship was still dealt and is counted by effects that track the
  amount of damage done to a player. In addition, Worship does not
  prevent loss of life, so loss of life bypasses Worship.