I suppose you could identify as a Christian without believing in the resurrection, but why would you? Christianity has no power and no hope apart from the resurrection of Christ. That would be like declaring yourself a life-long supporter of a team with no possibility of ever winning a game—or of claiming to be an heir of someone with zero inheritance to bequeath. Why bother?
The validity of the resurrection is utterly central to the claims of Christ, and therefore, to Christianity. The resurrected Son of God—the one the creeds say was “crucified, dead and buried,” then “rose again on the third day”—is the bedrock upon which all the promises of the Gospel rest.
The Apostle Paul, whose conversion from sworn enemy of Christ to relentless ambassador for Christ, changed the entire course of his life (and history!) after he met the resurrected Jesus on the road to Damascus. Paul, a devout Jew, had been hunting down Christians and delivering them over to Roman authorities before he met Jesus in the flesh. He knew the story told by followers of Jesus: of his life, his teachings, his death, and his resurrection, but Paul was having none of that until the resurrected Jesus appeared to him. The proof of the resurrection made Paul a believer, and the rest is history.
Paul’s response to the idea that there was validity to Christianity apart from the resurrection leaves us little room for doubt. In a letter to the church at Corinth he wrote,
But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead? If there is no resurrection of the dead, then not even Christ has been raised. And if Christ has not been raised, our preaching is useless and so is your faith. More than that, we are then found to be false witnesses about God, for we have testified about God that he raised Christ from the dead. But he did not raise him if in fact the dead are not raised. For if the dead are not raised, then Christ has not been raised either. And if Christ has not been raised, your faith is futile; you are still in your sins. Then those also who have fallen asleep in Christ are lost. If only for this life we have hope in Christ, we are of all people most to be pitied.
The heart of Christianity is a risen Jesus.
1 Corinthians 15:12-19 12But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead? 13 If there is no resurrection of the dead, then not even Christ has been raised. 14 And if Christ has not been raised, our preaching is useless and so is your faith. 15 More than that, we are then found to be false witnesses about God, for we have testified about God that he raised Christ from the dead. But he did not raise him if in fact the dead are not raised. 16 For if the dead are not raised, then Christ has not been raised either. 17 And if Christ has not been raised, your faith is futile; you are still in your sins. 18 Then those also who have fallen asleep in Christ are lost. 19 If only for this life we have hope in Christ, we are of all people most to be pitied.