Invitational Sunday

Last night after institute the branch president, who is amazing, pulled me into his office. We were chatting about life and how I am battling getting my certification- yes still! After we were talking for a little bit he was like I have two things to ask you. One is about a calling and the other is about invitational Sunday. I believe invitational Sunday is a stake thing that each ward is doing individually. Anyway, on May 23 the singles branch is having their Invitational Sunday where the members are encouraged to bring non-members and less actives to church with them. Missionaries from around the stake will be there I believe and it sounds like a really big deal. Well, he asked me if I would speak at it about the Atonement or Restoration or something along those lines. Good thing I have a week and a half to think about it. President Vaughan told me if I need any help to let him know and he would be glad to help. Besides asking for his help, I am also asking you guys for thoughts/ideas on this topic. I am excited to give a talk about it but have no idea what to talk about, especially with everyone that is supposed to be there. I am kind of intimidated about the whole thing. Oh and it has to be 15-20 minutes too! Please send me your thought and ideas to help with this. He really wanted me to focus on the Atonement or Restoration but I could talk about Joseph Smith, the Book of Mormon, things that go along with either of those two main topics if needed. HELP!!!!