The pastimes of Lord being eternal are beyond the comprehension of human material non-eternal sense organs. The Supreme Personality of Godhead is Absolute; hence His pastimes are also Absolute. One usually wonders, Mother Sita was kidnapped by a demon Ravana? Mother Sita is potency of Lord Rama. How can a demon living in Tama Guna even think to go near the potency of Absolute Godhead? Kurma Purana states before the arrival of Ravana, Lord Rama stated to Mother Sita, "Devi! Time has come. Please do the needful". Mother Sita arranged for a fire and entered the fire. This fire was the medium for her return to her abode. As Mother Sita entered the fire, from the other side, appeared another Sita that was replica of Mother Sita, "Maya Sita". Ravana kidnapped this very "Maya Sita". Before leaving for Ayodhya at the time of Agni-Pariksha, Maya Sita returned to the fire and Mother Sita re-appeared from the fire.
Our senses are limited. We cannot see beyond a particular distance nor can we see very clearly if the object placed is too near to our eyes. Similarly we are able to hear that is audible to us. Too loud or too low is beyond of ears. We cannot taste very hot, nor can we swallow extra chilled. Our intelligence is non-eternal as our other senses. Our intelligence is material. Then how can we perceive something eternal or Absolute with our material non-eternal senses? With our material non-eternal senses we cannot understand and apply logic to pastimes of Lord, which are Absolute like Him. We must better accept them as it is and meditate upon them for the pleasure of the Absolute.
When Sri Vibhishana approached Lord Rama, after consulting Lord Shiva, Sri Hanumana informed Lord Rama about his arrival. Everybody in Lord Rama's camp was agitated and wanted to kill Ravana's brother. But Sri Hanumana asked them to wait for Lord Rama. Lord Rama came and his army generals narrated to Him the details. Lord Rama smiled and said, "Oh! What to say of Vibhishana? Even if Ravana comes and surrenders unto me by merely saying "I surrender unto You", I shall forgive him. Anyone with true heart need to say "O Rama! I am yours", I take him under my shelter".