"The owner of this website (bjp.org) has banned your IP address on the country or region you are accessing it from." This is error which is currently being displayed whenever someone tries to access the bjp.org from Pakistan.
At the time of writing, even the BJP's PM candidate Narendra Modi's website(narendramodi.in) has also been blocked for Pakistan and showing some error message.
This move comes after Pakistan hackers targeted BJP related website and defaced BJP's Leader LK Advani's website and Bihar BJP websites in last two days.
The website can be still accessed by users from Pakistan by using proxies to mask their IP addresses. If the website is secure against all attacks, then there will be need for such wide range of IP blocks except in cases of DDOS attacks. Even then, only individual IPs usually need to be blocked.
Arvind Gupta, BJP IT Cell Heaad, told NewsWeek that the site had been blocked in Pakistan "automatically" as a security measure and they had request CERT-India to unblock the sites.