I think this "player" likes me..?

I met this guy at a party. He was really nice. We went on the roof, talked and laugh. Thing is he turned out to be my brother's gf brother. He got my number and we've been texting. My brother says to stay away from him because he is a player. He parties allot, sleeps around and stuff. He invited me to church which was confusing because of the stuff he does. I made up an excuse to not go by saying I have to go to the museum and invited him knowing he'd say no (what guy wants to spend a day in a museum?) anyways he wants to go. We talked on the phone and turns out we have allot in common. But his rep is really bad. But he's been nice to me. He also called my brother and asked him for permission to talk to me. I don't believe anything he tells me because of the things people say. What should I do? Btw we 17