My 4 year old son's behaviour...help!!!?

I hope someone here can help. I am a mum of three amy is ten chase is four and chloe is 5 months (the older two are from a previous relationship) My partner has never dealt with or had kids before meeting me almost 2 years ago. My son has started school and is a very stubborn little boy. I use the step and removal of toys and privileges as punishments. However my partner doesn't agree. He shouts at him like he is shouting at an adult and then when he cries he calls him a pansy. I have told him several times that i am not willing to put up with this as my little boy now thinks paul doesn't like him. I love my partner but next to kids there is no comparison. The thing is he is an amazing and supportive partner,this is the only issue we have. He says that he doesn't want chase growing up to be a delinquent and he would rather he was afraid of him and behaved,but this isn't healthy i know this. I am hoping there is some way i can show him to deal with this issue. Any help? Laura