If He had not arisen, our Faith would be in vain.
Because His resurrection was necessary for His sacrifice to be accepted by God ?
No. His resurrection was indeed a miracle. Miracles were, and continue to be EVIDENCE, historically recorded by many sources and testimonies of those that witnessed them, Evidence, proof, That Jesus Christ was who he said was - The Son (only Son) of God.
Was that Evidence sufficient ? Many would assume so, but even for one of Christ's disciples, it was not. Even for a very devout Man of God, who believed in the Holy Scriptures, accepted that there was only One True God, believed that there WOULD be a Saviour, as promised in the Scriptures, believed that Christ would be the Saviour, was known as the 'pharisee of pharisees' did not accept the evidence of His resurrection.
The first man is commonly known as Doubting Thomas. He refused to believe until he could see the Risen Lord with His own two hands, place his hand in the wound from the Sword, place his fingers in the holes that the nails had pierced the hands of Christ. Then, and only then, would he 'believe'.
The second man made it his life's work to hunt down ALL followers of Christ, put them to death - and did so until he was struck blind on the road to Damascus, and heard it straight from God's own lips. That man was Saul, who after that, became Paul, an apostle of Christ.
Now, maybe it can be understood why I, a sinful mortal human being do not even attempt to prove that God is Whom He Says He is. No matter what 'evidence' I could offer (from science, from excellent persuasion, from any words, experiments, brilliant sermons or any other means), it would be futile.
Only God himself can give 'Faith' to man.
The Resurrection is indeed 'miraculous', worthy of celebration, and of great import.
There is something that is even more important. And that occurred on Good Friday. No, not the sacrifice of Christ, not His Crucifiction.
It is what GOD did on Good Friday. [b]He accepted that sacrifice, the sacrifice of ONE MAN, for the sins of ALL HUMANITY, present, past, and future, as sufficient payment for the price of their sins. Was that what we humans call justice - letting someone else be blamed and punished, someone totally innocent of committing ANY sin ? No, that is not what we humans would accept as 'human justice'.
It IS what God considered - final justice.
HE RECONCILED ALL OF CREATION TO HIMSELF. And that is what it was and is all about. HE DID IT - not we.
It is finished.

Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good ...