It's like if you need to build a house, and there's a person who is very skilled at construction, but at the same time, he is a habitual murderer, rapist, and thief. Now, would you say, "I don't care, I'll just use his construction skills to build the house first." Aren't you worried that after he finishes building the house, he will kill your family, rape the women, and steal your belongings?