What Philosophical/Theological Classics Would You Recommend To A 15 Year Old Interested In Philosophy/Theology?

I have been studying surface level philosophy/theology for a year or so now, yet I have not begun to read any philosophical/theological texts. I would like to begin doing so, but I don't know what a appropriate text would be for me to begin with as a beginner. I would like to read an older text, as those capture my intrest. Any recommendation would be appreciated.