Do we Hindus have to learn concept of one god from Islam or Christianity?

प्रणाम (PRANAAM )/GREETINGS-------------------NO, WE ONLY HAVE TO UNDERSTAND THE CONCEPT OF GOD IN HINDUISM PROPERLY. PLEASE READ THE NEXT PARAGRAPH TO KNOW FURTHERGOD-ISHWAR, PARMATMA, BHAGWAN & DEVTA These are the four words used in Hinduism for GOD . Lets see a little explanation about these words to understand the differenceISHWAR /PARMATMA(ईश्वर)-Ishwar is one & only one. It is

How would India have been if there were no Islamic invasion?

No Islamic invasion means no Muslims. There are hundreds of negative things that would have never happened to India but there are some reasons for which everything that happened is worth it.India wouldn't have been tolerant. With the Muslims gone, we would never have had interactions with other religion, we would have never tried to understand

Why did India not have a Reconquista like Spain did?

It did, when the Maratha Confederacy managed to conquer from South India to Punjab. The Marathas were generally much more tolerant than the Christian Spanish crusaders, but their conquest led to a resurgence of Hinduism, and they built many temples and shrines along the way. Shivaji, the founder of the empire, wrote a letter to the Mughal emperor