I will give a very simple answer for your good question.
In simple terms if the death and resurrection did not happened then we have no way to enter God's Kingdom.But since it happened we must be thankful for the Mercy of God thru Jesus Christ offering of his own life for our redemption and opening again the door for us towards salvation.
In Catholic Faith, three things are essential Baptism, Reconcilliation and Holy Eucharist.
1.The Sacrament of Baptism washes away the original sin we contracted thru Adam's fault to restore Divine Life in our soul.
2.But since a Christian journey does not end in Baptism and a faithful is commanded to perfection like our Father in Heaven, the Sacrament of Reconcilliation was also instituted for us be healed again whenever we fall into sin.God infinite mercy is being offered to us by our loving and merciful Father to continue to restore us again.
3.Since the blood of Christ washes away our sins but the stain of the original sin in our soul remains, what the Catholic Faith called concupiscence, one will need the Holy Eucharist to wash away the stain of one soul.Since the very body,blood, soul & divinity of Christ enters our inner being it help us overcome our concupiscence or inclination to sin.
The results of this three essential sacraments is, by Baptism the Divine Life was restored and if we fall back into sin the Sacrament of Reconcilliation restore back the Divine Life again and the most important thing for us Catholic is the Holy Eucharist because partaking it will give us Eternal Life.(John6:53-55)
From restoration of Divine Life to possessing Eternal Life is the sweet christian journey of every catholic faith.But ofcourse the road to salvation that Jesus teaches as he came down to show us the way, is the Way of the Cross.
In the end we can confidently echo what St.Paul had exclaimed that earn him his own perfect and complete salvation, "I have crucified my flesh, it is no longer I who lived but Jesus"(Galatians2:20)
Like St.Paul, we fulfilled what the Abba Father had required of us to merit Heaven " Be perfect therefore as your Heavenly Father is perfect".Our perfection is based on our cooperation and union to God's Will and it is not a freegift like other christian faith teaches.Our perfection was earn by embracing our own Way of the Cross for our own glorious resurrection like Christ.
When we reach Heaven with our resurrected bodies, we will be crown according the works we had done and not simply claiming what Jesus had given us as a freegift, the crown is really is our cooperation and we merit it like all the Saints and Martyrs in Heaven had gone thru.
This is the simple summary of Catholic Faith about the meaning of Christ death and resurrection, for full explanation see the Catechism of the Catholic Church.