You can't force a cat to do anything so you need to convince him that inside is a great place to be. Do this by hiding cat food around the home so that he stalks around to find it (instead of putting a bowl of food down). Provide a calm environment with plenty of hiding places (cardboard boxes will do) and places he can perch up high to feel safe ( a cat tree) . When the cat approaches you, stroke and pet him, perhaps offering a treat so that he links you to pleasant things and then wants to spend more time with you.