This is hard. A 13-year-old isn't a little child anymore, but isn't an adult either. At 13 they're working hard to become the adult they're going to be, and because of that there's a LOT of friction.
As parents, we need to strike a balance between maintaining our authority and family order (rules, discipline), and allowing our young people to become the individuals God has made them to be.
With a younger child, you are in authority because you are the parent. With an older child, they have to be willing to submit to your authority. This is something that is much easier if they already have the habit of submitting to you from their younger years, but if you've been butting heads his entire life (as I assume from your "strong willed" comment), he hasn't done anything willingly. Ever.
IMHO, your job will be to 1) pray, and 2) help him make the right, God-honoring decisions for his life, including continuing to live under your authority until he's grown, and 3) continue praying.
Also, IMHO, the worst thing you can do is try to force your authority on him. He will only rebel, making things much worse. Keep in mind he is no longer a child - treat him as a young, inexperienced adult. Expect him to be able to make adult decisions and take adult consequences. (Within the confines of his age - a 13 yo's consequences should look very different from an 18 yo's consequences). Give him adult responsibilities (perhaps setting his own bedtime on weekends - making it clear he's expected to be responsible for his commitments in the morning too, such as getting up for church on time) and help him make adult choices with much input and discussion from you.
This is the age to be honest with your son - not to the point of revealing the intimate details of your younger years, but sharing some of the struggles and accomplishments you had when you were his age. Let him know you understand what he's going through - even though he'll say you can't understand.
Let him earn your trust in little things, and then trust him with bigger things.
And do devotions with him - Elisabeth Elliot's "The Mark of a Man" is a book I used with my boys. Their father spends other time with them - discussing theology, politics, etc.
I know I haven't given you a quick fix answer, but there isn't one. Of course, while you work on the big picture, you must insist that he follow the family rules and respect you (especially if there are younger siblings around) - but it goes two ways. You must respect him, too.
A thirteen year old longs for the same unconditional love you gave him when he was three. Remember toilet training? And the entire gallons of milk spilled on the floor? And eating the dog food? Draw on the same God-given patience and love you had then.
Oh, and hormones. Don't forget to take raging hormones into account. Give him a LOT of outdoor activity. At this age my boys went camping every month (year around) with their Boy Scout troop. That helped immensely with the urge to do Big Things.
And I just realized I've been addressing this as if your child is a boy, but you didn't say. The same advice goes for girls, too, except they also benefit from godly older girls who are willing to share their lives with them. Girls need friends - we learn more from talking than doing, it seems!