First of all, just because you have doubts does not mean that you don’t believe. If one wills to believe, one believes. I expect that you do believe. Listening to or reading debates between atheists and believers isn’t going to do it for you. It’s not just a matter of finding the right argument. It’s a matter of meeting a Person. As a favor to me and to yourself, spend a half hour before his presence in the tabernacle for a month. It’s OK if you miss a day or two. But try to make it every day. Tell the Lord that you want to believe in him and all that the Church teaches about him. And then just sit. Let him do the work.