Why is it necessary to pray for enemies? It is necessary not only for them, but for us as well. We should find in ourselves the strength to be reconciled with people. Archimandrite Sophrony (Sakharov), in his book about St. Silouan the Athonite, says, "Those that hate and reject their brother are flawed in their being; they cannot find the way to God, who loves all." This holds true. When hatred for man settles in our heart, we are not able to approach God. As long as we hold on to this feeling, the path to God is barred to us. This is why it is necessary to pray for our enemies.
+Metropolitan Hilarion (Alfeyev), from Prayer: Encounter with the Living God, #13 Prayer for Our Enemies