People say if muslims are not allowed to take non muslim as friends. then how should you convert them to Islam?

There are many ways. We can hide our faith and preach to them, what we can do is lie by saying we can be friends, this is called taqqiya.

or allah can guide them to Islam. Allah says he guides who he pleases, and misguides who he pelases. Allah says that he has blinded some people.These ppl can not ever become muslim or understanding islam. Allah chooses who to misguide.

Muslims are allowed to treat non muslims kindly (Quran 60:8), and that wud NOT be taking them as friends. We are allowed to do that. However, just because allah says we are allowed to treat them kindly.Doesnt mean we shud go out of our way to do this, it is not compulsory. does not mean we should. The verse about kindess was reavealed in the context of Abu Bakr's (RA) daughter and wife. His daughter(who was muslim) did not let her mother (who was disbeliever) enter the house. So allah revealed this verse. Some wud say, muslims are only allowed to treat disbelieving mothers kindly. But in Islam gods word is final.