I don't have a sufficient answer to this question, but I will give you something else. If you are surprised that the Lord Jesus says this, then why aren't you surprised that God Himself says, "O Prophet, urge the believers to fight. If there are among you twenty [who are] steadfast, they will overcome two hundred. And if there are among you one hundred, they will overcome a thousand of those who have disbelieved because they are a people who do not understand. Now God has lightened your burden, for He knows that there is weakness in you. So if there are among you one hundred..." Those who are patient will overcome two hundred, and if there are a thousand of you, they will overcome two thousand by permission of Allah. And Allah is with the patient.
ليس لدي الاجابه الكافيه لهذا السوال ولكن سوف اعطيك شي اخر اذا كنت تستغرب من الرب يسوع يقول هذا الشي فلماذا لا تستغرب من الله نفسه حين يقول ليعلم يَا أَيُّهَا النَّبِيُّ حَرِّضِ الْمُؤْمِنِينَ عَلَى الْقِتَالِ إِنْ يَكُنْ مِنْكُمْ عِشْرُونَ صَابِرُونَ يَغْلِبُوا مِائَتَيْنِ وَإِنْ يَكُنْ مِنْكُمْ مِائَةٌ يَغْلِبُوا أَلْفًا مِنَ الَّذِينَ كَفَرُوا بِأَنَّهُمْ قَوْمٌ لَا يَفْقَهُونَ * الْآنَ خَفَّفَ اللَّهُ عَنْكُمْ وَعَلِمَ أَنَّ فِيكُمْ ضَعْفًا فَإِنْ يَكُنْ مِنْكُمْ مِائَةٌ صَابِرَةٌ يَغْلِبُوا مِائَتَيْنِ وَإِنْ يَكُنْ مِنْكُمْ أَلْفٌ يَغْلِبُوا أَلْفَيْنِ بِإِذْنِ اللَّهِ وَاللَّهُ مَعَ الصَّابِرِينَ