Whoever knows the mystery of the cross and the tomb knows the meaning of things.
— St. Maximus the Confessor
The Catechism of the Catholic Church in paragraph #618 states that:
The cross is the unique sacrifice of Christ, the “one mediator between God and men”. But because in his incarnate divine person he has in some way united himself to every man, “the possibility of being made partners, in a way known to God, in the paschal mystery” is offered to all men. He calls his disciples to “take up [their] cross and follow [him]”, for “Christ also suffered for [us], leaving [us] an example so that [we] should follow in his steps.” In fact Jesus desires to associate with his redeeming sacrifice those who were to be its first beneficiaries. This is achieved supremely in the case of his mother, who was associated more intimately than any other person in the mystery of his redemptive suffering.
Apart from the cross there is no other ladder by which we may get to heaven.