Why do Christan's always p judgment on people?

My dad`s last name is mohammad even though he now belives god is man he never openly just critize Christanity although he knows the bible more then most christans do. Every time he goes in a church(he studies religon) and they asked for his name and he says it the response of the christan is whoo you need to be saved with the blood of jesus or you going to burn in hell if you dont say jesus is your lord and savior one person said my dad was going to burn in hell forever and my dad responded(Hell most not be so hot if you can be in it forever and not acualy burn then he left the church but everytime he says his time like 40 people come up to him trying to teach him the word of the bible and how he needs to be saved my dad is a grown man and the smartest person i know . And my dad is peacfull he never wants revenge or anything he follows of the rules christan`s are suppose to follow expect he dosent belive that god is a mystery spook and why do you p judgement on him when only god can