Members of religious cults often are strongly convinced that they, and they alone, are right, and everyone else is wrong. Your aunt may very well be like this. Unfortunately, members of cults also are often very hard to convince that they might be wrong. Some cults have a very strong central leader, and their members are afraid of resisting him. Other cults make their members feel very proud because they alone know the truth, and they become close-minded because they can't bear the thought that they might be wrong. The Bible warns that pride often blinds us to God: "In his pride the wicked does not seek him; in all his thoughts there is no room for God" (Psalm 10:4).
My point is this: Don't be surprised if your aunt keeps on sending you material and trying to convert you, no matter what you say to her. Yes, politely but clearly tell her you aren't interested. But don't be surprised if she refuses to listen. Instead, pray for her, and ask God to show her the truth–which is the Good News about Jesus. Down inside she is on a spiritual search–and only the living God can satisfy her inner hunger. And if you have never given your own life to Jesus Christ, do so without delay.