In the Psychology class, the teacher showed us some research that concluded humans may live longer when they are religious.
In these studies, they didn’t specify which religion they followed, so I guess it might include many religious beliefs.
How can we, as Muslims, explain that the lifespan of the kuffar increases if they are religious? This is especially because we know that Allah does not answer their prayers when they engage in idol worship and deal with jinn.
Yes, the studies in the videos show that all human beings, regardless of the religion they follow, live longer if they are religious.
Looking at this from an Islamic perspective, we know that Allah prolongs the lives of the believers. However, there are some verses which state that He also prolongs the lives of the disbelievers. Here are a few:
بَلۡ مَتَّعۡنَا هَـٰٓؤُلَآءِ وَءَابَآءَهُمۡ حَتَّىٰ طَالَ عَلَيۡهِمُ ٱلۡعُمُرُۗ أَفَلَا يَرَوۡنَ أَنَّا نَأۡتِى ٱلۡأَرۡضَ نَنقُصُهَا مِنۡ أَطۡرَافِهَآۚ أَفَهُمُ ٱلۡغَـٰلِبُونَ
"But, [on the contrary], We have provided good things for these [disbelievers] and their fathers until life was prolonged for them. Then do they not see that We set upon the land, reducing it from its borders? So it is they who will overcome?" 
وَلَا يَحۡسَبَنَّ ٱلَّذِينَ كَفَرُوٓاْ أَنَّمَا نُمۡلِى لَهُمۡ خَيۡرٌ۬ لِّأَنفُسِہِمۡۚ إِنَّمَا نُمۡلِى لَهُمۡ لِيَزۡدَادُوٓاْ إِثۡمً۬اۚ وَلَهُمۡ عَذَابٌ۬ مُّهِينٌ۬
"Let not the unbelievers think that We prolong their days for their own good. We give them respite only so that they may commit more grievous sins. Shameful punishment awaits them." 
As you can see from the above verse, prolonging the life of the disbelievers can be a punishment in itself.
And Allah knows best.
 Qur’an, 21:44
 Qur’an, 3:178< Back to Questions