What should I do about this guy?

He goes to my church and his a nice guy and all. Two years prior,he asked me to go out with him and not wanting to seem mean I said ok, but kinda flaked on him. We never shared a proper conversation, and he used to send me messages about being more than friends, which I didn't want and let him know that friendship was all I was interested in. But all the while he used to come with this girl, who i'm very sure was his girlfriend. But anyway that's the history of the situation in a nutshell. Now, he called me up again, getting my number from his aunt and asked me to be friends and that he'd like to take me out and how nervous I make him. And that the girl he brought to church all those times is travelling abroad and that she was just his friend. So you see his persistant and doesn't to get a hint, what should i do? I'm fine on my own, why can't he see that.