The highest degree of belief in Islam is love; you are speaking without knowledge and if you read about Islam you would know that it is a fair religion that gives every person own rights within the limits of God. Again read about prophet Jesus peace be upon him in the previous link (he is not God, he is not the son of God, he is only a human and we (Muslim people) are waiting for his return).

Also, there is a dispute about the age of one of the wives of prophet Mohamed peace be upon him and in some narration it is said to be 14 years old and that marriage in that age was common at their time and not wrong at all. The wife in concern is also one of the most knowledgeable that used to be a reference to teach the Islamic religion.

Anyways, regarding the marriage age in Islam, it’s advised to test the judgement of the person in order to decide if they are able to face marriage or not and it’s also advisable to get married early. 

Only recently the marriage age was brought to 18 years old. However even in Europe not long ago, girls used to get married as early as 14 years old or even earlier.

So from my opinion we can’t judge the customs or marriage age of more than 1400 years ago or seek to apply terms that were introduced recently on people of that time. 

4:6 Nasa

‎وَابْتَلُوا الْيَتَامَىٰ حَتَّىٰ إِذَا بَلَغُوا النِّكَاحَ فَإِنْ آنَسْتُمْ مِنْهُمْ رُشْدًا فَادْفَعُوا إِلَيْهِمْ أَمْوَالَهُمْ ۖ وَلَا تَأْكُلُوهَا إِسْرَافًا وَبِدَارًا أَنْ يَكْبَرُوا ۚ وَمَنْ كَانَ غَنِيًّا فَلْيَسْتَعْفِفْ ۖ وَمَنْ كَانَ فَقِيرًا فَلْيَأْكُلْ بِالْمَعْرُوفِ ۚ فَإِذَا دَفَعْتُمْ إِلَيْهِمْ أَمْوَالَهُمْ فَأَشْهِدُوا عَلَيْهِمْ ۚ وَكَفَىٰ بِاللَّهِ حَسِيبًا

And test the orphans [in their abilities] until they reach marriageable age. Then if you perceive in them sound judgement, release their property to them. And do not consume it excessively and quickly, [anticipating] that they will grow up. And whoever, [when acting as guardian], is self-sufficient should refrain [from taking a fee]; and whoever is poor - let him take according to what is acceptable. Then when you release their property to them, bring witnesses upon them. And sufficient is Allah as Accountant.