[SPOILER FOR ENDING] Horror/Religion film [SOLVED]

[Edit] I haven't been able to watch it but I'm sure sslssg has it right.[Edit]

I thought I could sort this with a simple google search but alas I'm here. I remember watching a movie around the early 90's possibly late 80's about a young man, could even be a up and coming priest that is to be the host for the devil or something. I remember a woman helping him out and trying to stop it but in the end there is a cut to the radio in the car then to his face and he smiles leading the audience to the conclusion he was indeed possessed. I believed they are parked near railway tracks. I really thought the actor was called Ben Johnson, like his first and maybe only film. I also thought the movie had a one/two word title.