Sacrifices for sin (in the Old Testament) were for some known or remembered sins, or for unknown sins. There were sins that resulted in capital punishment for which there was no provision for atoning sacrifice.
Lev.6:30 And no sin offering, whereof any of the blood is brought into the tabernacle of the congregation to reconcile withal in the holy place, shall be eaten: it shall be burnt in the fire.
I Sam. 3:14 And therefore I have sworn unto the house of Eli, that the iniquity of Eli’s house shall not be purged with sacrifice nor offering for ever.
Jer.6:20 To what purpose cometh there to me incense from Sheba, and the sweet cane from a far country? your burnt offerings are not acceptable, nor your sacrifices sweet unto me.
Heb.10:4 For it is not possible that the blood of bulls and of goats should take away sins.
Heb.9:26 For then must he often have suffered since the foundation of the world: but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself.
Ps. 50:5 Gather my saints together unto me; those that have made a covenant with me by sacrifice. - (WHOLE CHAPTER)
I Sam.15:22 And Samuel said, Hath the LORD as great delight in burnt offerings and sacrifices, as in obeying the voice of the LORD? Behold, to obey is better than sacrifice, and to hearken than the fat of rams.
Ps. 51:16 For thou desirest not sacrifice; else would I give it: thou delightest not in burnt offering.
51:17 The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise.
Pr. 21:3 To do justice and judgment is more acceptable to the LORD than sacrifice.
21:27 The sacrifice of the wicked is abomination: how much more, when he bringeth it with a wicked mind?
Hos. 6:6 For I desired mercy, and not sacrifice; and the knowledge of God more than burnt offerings.
Num 9
9:1 And the LORD spake unto Moses in the wilderness of Sinai, in the
first month of the second year after they were come out of the land
of Egypt, saying,
9:2 Let the children of Israel also keep the passover at his appointed
season.
9:3 In the fourteenth day of this month, at even, ye shall keep it in his
appointed season: according to all the rites of it, and according to
all the ceremonies thereof, shall ye keep it.
9:4 And Moses spake unto the children of Israel, that they should keep
the passover.
9:5 And they kept the passover on the fourteenth day of the first month
at even in the wilderness of Sinai: according to all that the LORD
commanded Moses, so did the children of Israel.
9:6 And there were certain men, who were defiled by the dead body of
a man, that they could not keep the passover on that day: and they
came before Moses and before Aaron on that day:
9:7 And those men said unto him, We are defiled by the dead body of a
man: wherefore are we kept back, that we may not offer an
offering of the LORD in his appointed season among the children
of Israel?
9:8 And Moses said unto them, Stand still, and I will hear what the
LORD will command concerning you.
9:9 And the LORD spake unto Moses, saying,
9:10 Speak unto the children of Israel, saying, If any man of you or of
your posterity shall be unclean by reason of a dead body, or be in a
journey afar off, yet he shall keep the passover unto the LORD.
9:11 The fourteenth day of the second month at even they shall keep it,
and eat it with unleavened bread and bitter herbs.
9:12 They shall leave none of it unto the morning, nor break any bone of
it: according to all the ordinances of the passover they shall keep it.
9:13 But the man that is clean, and is not in a journey, and forbeareth to
keep the passover, even the same soul shall be cut off from among
his people: because he brought not the offering of the LORD in his
appointed season, that man shall bear his sin. (Jesus is our Passover Lamb!!!)
if we repent of our sins and turn Jesus, then He will forgive all of our sins!