The Wicked Son Redeemed?

And as has been said numerous times, based on the language of the sages in the response to the question of the "wicked son" in the Pesach Haggada: "if he was there, he wouldn't have been redeemed"—that it seems perplexing: what is the need and what is the benefit from telling a wicked one that he has no connection to the Seder, which is in rememberance of the Exodus from Egypt? The explanation is that the intention is not to push away the "wicked son" from the Seder and to inform him that the redemption is beyond him, on the contrary—the response to him emphasizes that only "there (in Egypt) he wouldn't have been redeemed", but in the future redemption, since it follows after the giving of the Torah, he too will be redeemed.

And this illustrates to us, in passing, the wonderous effect of Matan Torah, where the Holy One blessed be He said "I am Hashem your G-d" in the singular, that YKVK is brought down to be the power and the life of every single member of bnei Yisroel, and therefore every Jew, even a wicked one like this, and so he is assured that through this power [which was bestowed upon him at Matan Torah] in the end he will be redeemed...

Lubavitcher Rebbe, Likutei Sichos XI, p.2