Serious people argue this both ways. Say so before your friend does.
Leviticus 17:11 is direct: "it is the blood that maketh an atonement for the soul." Atonement happens through blood placed on an altar. That altar stood in the Temple in Jerusalem, and nowhere else.
Rome destroyed the Temple in AD 70. It has never been rebuilt.
So the one thing Leviticus names as the means of atonement has been gone for nineteen centuries.
With prayer, repentance and acts of kindness. This is a serious answer, worked out by people facing a catastrophe, and it has carried Judaism for a very long time.
Treat it with respect or the conversation is over.
The Torah names blood on an altar. The rabbinic answer names something else.
So: where does the Torah authorise the replacement? Ask it gently, once, and then stop talking.
Contested. The question is real and hard.
The Jewish answer is not stupid, and treating it as stupid will end the conversation on the spot.
"Leviticus 17:11 grounds atonement in blood on an altar. What grounds it now?"



The Bible forgives without blood too: flour, Nineveh, and a broken heart.
This answer is solid, and it is made from the Bible rather than around it. The Hebrew Bible shows atonement without blood more than once. A poor Israelite brings a flour sin-offering in Leviticus 5:11-13. There is no blood at all, and yet 'the priest shall make atonement.' Hosea 14:2 offers the words of repentant lips instead of bulls.
Solomon's prayer at the dedication, in 1 Kings 8:46-50, expects forgiveness with no Temple, through prayer and turning back. Daniel prayed without a Temple. Nineveh was forgiven for repentance alone in Jonah 3:10. Psalm 51:17 says the sacrifices of God are a broken spirit.
And Hosea 6:6 — 'I desire mercy, not sacrifice' — was quoted by Rabbi Yochanan ben Zakkai after the Temple fell, and by Jesus in Matthew 9:13. Leviticus 17:11, they add, is about eating blood, not a monopoly on forgiveness.
Contested, and their case is real Bible, so ask the question, don't claim a win.
Graded Contested — this counter-case is real Bible, not evasion. Flour offerings, Nineveh and Psalm 51 have to be conceded. The claim that 'Judaism has no answer for sin' is simply false, and this site should say so plainly.
The open question is narrower, and worth asking carefully rather than in triumph. The Torah's own centre of gravity for atonement is Yom Kippur, the altar and the blood. Judaism after 70 AD had to build a system without them. Asking where the Torah authorises that is a fair question. Claiming Judaism has nothing to say is not.