The sin of murder will cause the Fire of Sin to deal a lethal blow to an enemy. The higher the number of murders that the enemy had committed, the more lethal blows they would receive from the Sin of Fire.
The damage of the Sin of Fire is entirely dependent on the number of sins, not the spiritual power of the judge or the spiritual power of the enemy. The spiritual power of the judge who uses the Fire of Sin only affects how fast the Fire burns and how quickly it damages the enemy.
But the murder of a lamp bearer means that the enemy will surely die after the fire of sin is used against it. The god of justice has decreed it, so the Fire of Sin will involve the power of a god as long as the enemy has killed a lamp bearer before.
Because of the decree of the god of justice, it doesn't matter how long it will take, the sin of killing a lamp bearer will lead to death when the fire of sin is used.
