Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) once mentioned:
As long as one does not acquire sound understanding in Deen and become firmly established upon Deen, there will always be the fear that such a person will transgress the limits and boundaries in his actions. Since such a person does not know the limits, if he befriends someone he will transgress the limits in friendship and if he has enmity for someone, he will transgress the limits in his enmity. Both situations are extremely detrimental. In essence, the outcome of dealing with such a person who is not firmly established in Deen and does not know the limits can prove disastrous. There was once an ‘Aalim who was of the opinion that Muslims should go into partnerships with Hindus. When he expressed his opinion to me, I told him, “We cannot, with certainty, say what will be the outcome of such a Muslim’s dunya. However, the harm that will come to his Deen is quite clear and evident. This is due to the fact that Hindus, in reality, don’t have any Deen and hence do not adhere to the limits of Shari’ah. If the Muslim tries to uphold Deen in the partnership, then how will the partnership continue? On the contrary, if the partnership continues in the way the Hindu wishes, then how will the Muslim uphold his Deen? The reason is that every decision the Hindus will make will be centred around dunya and material progress even if it opposes the laws of Deen. They will do whatever they deem necessary in order to boost their business in the pursuit of worldly progress. How then can a Mu’min’s Deen be secure and safe if he has to adopt their ways? (Malfoozaat Hakeemul Ummat 8/239)