I attended a Christian college for my undergrad studies (public for my Master's degree) and I've taught for more than 17 years (out of 28 total) in three private religious schools; I stay in touch with former students, as well. So, I think I can offer something to this discussion. I concur with the ideas above and would add a few more:
1. Accountability. In a smaller environment where class sizes are smaller and teachers really do know their students, it's more difficult just to get by. Expectations are higher and mediocrity is generally not acceptable because we understand that God expects us to give our best efforts. Students who would typically get "lost" or overlooked in a larger school will be seen and encouraged, allowing them to flourish in ways they would not in a public school setting.
2. Opportunity. While these kinds of schools are generally smaller and don't necessarily offer as wide a variety of extracurricular activities, more students are able to get involved in those which are offered. This allows the directors, coaches, advisers, and sponsors to act as spiritual mentors for their students. For me, this was the best part of teaching in these schools, and it's the reason I have so many ongoing long-term relationships with my students. They know they have someone in their corner who loves them and prays for them in the good times and the bad.
3. Worldview. We all have a worldview, and a religious education really allows students to learn what they believe and why they believe it. One of the tragedies of life is that so many high school students have a crisis of faith after leaving whatever high school they attended; having a strong grounding will help those students persevere and grow if and when they have such a crisis.
I assume you're looking for positive elements of religious education, based on your question; if not, there is an entirely different set of issues.
I went to Lutheran schools from Kindergarten until 8th grade and then went into a public high school. After that, I again attended a Lutheran college for my Bachelor's Degree, and went to a public university for my Masters.
After seeing both, I found at least three reasons for religious education influences your life:
1. IT IS DEFINITELY MORE ACADEMICALLY CHALLENGING that public education. I am not sure why that is. Perhaps is has to do with understanding how history and science and literature aligned with religion, or because only a certain clientele go to religious schools, or if people with religious background just expect more because their expectations are mixed with their moral code.
2. RELIGIOUS EDUCATION MEANS IMMEDIATELY APPLYING YOUR EDUCATION. Most religious education includes the effort to implement what is learned in life today. Because these lessons are moral values driven, this works. I found myself a more pleasant person during my religious education years because I liked who I was. I was improving myself by learning to be a servant to others and that felt good.
3. RELIGIOUS EDUCATION GIVES YOU HOPE. Often, in the real world, we cynically point out everything that is wrong with the world without offering solutions that will work. The premise of most religions is that there will be an afterlife and it is something to look forward to. This hope helps students have a positive outlook.
If you need a thesis, writing a thesis means you must take a stance about the topic. I have given you positive reasons to write about. You might consider a statement like this: Religious education offers several blessings to students.