Can’t we as Catholics just admit that atheist have the same chance of getting into heaven as us?
Fundamentals of Catholic Dogma, Ludwig Ott.
20. 'The Necessity for Membership of the Church
Membership of the Church is necessary for all men for salvation. (De fide.)
In the Caput Firmiter, the Fourth Lateran Council (1215) declared: “The universal Church of the faithful is one outside of which none is saved” (extra quam nullus omnino salvatur). D 430. This was the teaching also of the Union Council of Florence (D 714), and of Popes Innocent III (0 42)) and Boniface VIII in the Bull ‘Unam sanctam’ (D 468), Clement VI (D 570 b), Benedict XIV (D 1473), Pius IX (0 1647, 1677), Leo XI1I (0 1955), Pius XII in the Encyclical Mystici Corporis" (D 2286, 2.288).
As against modern religious indifferentism, Pius IX declared: “By Faith it is to be firmly held that outside the Apostolic Roman Church none can achieve salvation. This is the only ark of salvation. He who does not enter into it, will perish in the flood. Nevertheless equally certainly it is to be held that those who suffer from invincible ignorance of the true religion, are not for this reason guilty in the eyes of the Lord" (D 1647). The last proposition holds out the possibility that people who in point of fact (actu) do not belong to the Church can achieve salvation. C£ D 1677; 796 (votum baptismi).
The necessity for belonging to the Church is not merely a necessity of precept (necessitas praccepti), but also a necessity of means (nee. medii), as the comparison with the Ark, the means of salvation from the biblical flood, plainly shows. The necessity of means is, however, not an absolute necessity, but a hypothetical one. In special circumstances, namely, in the case of invincible ignorance or of incapability, actual membership of the Church can be replaced by the desire (votum) for the same. This need not be expressly (explicite) present, but can also be included in the moral readiness faithfully to fulfill the will of God (voturn implicitum). In this manner also those who are in fact outside the Catholic Church can achieve salvation.
Christ ordained affiliation to the Church by founding the Church as an institution unto salvation for all men. He endowed the Apostles with His authority, gave them a universal mandate to teach and baptize and made eternal salvation dependent on the acceptance of His teaching and the reception of Baptism. Luke 10, 16; Mt. 10, 40; 18, 17; 29,19; Mk.16, 15 et seq. That those who, in innocent ignorance, do not know the true Church of Christ, but who are nevertheless ready to bow to the demands of the Divine Will, will not be cast out, springs from the Divine Justice, and from the doctrine of God’s general will of salvation, which is clearly proved in the Scriptures. (1 Tim. 2, 4). The Apostles teach the necessity of the Church for salvation by promulgating Faith in Christ and His Gospel as a condition for salvation. Peter confesses before the High Council: “Neither is there salvation in any other" (Acts 4, 12). Cf Gal. I, 8; Tit. 3, 10 et seq.; 2 John 10 et seq.
It is the unanimous conviction of the Fathers that salvation cannot be achieved outside the Church. This principle was extended not only to pagans but to heretics and schismatics as well. St. Irenaeus teaches that: “in the efficacy of the spirit all those have no part, who do not hasten to the Church; rather they, by their evil teaching and their evil deeds, rob themselves of life. For where the Church is, there is also the spirit of God, and where the spirit of God is, there is the Church and all grace" (Adv. haer. III 24, I). Origen formally declares: “Outside the Church nobody will be saved” (extra ecclesiam nemo salvatur; In Jesu Nave hom. 3, 5); similarly St. Cyprian: “Outside the Church there is no salvation" (salus extra ecciesiam non est; Ep. 73, 21). The Fathers, for example, St. Cyprian, St. Jerome, St. Augustine, St. Fulgentius, regard, as types of the necessity of the Church for salvation, the saving Ark of Noah and the House of Rahab OOS. 2, 18 et seq.). In the Primitive Church the conviction of her necessity for salvation found practical expression in her missionary zeal, in the readiness of her children to suffer martyrdom and in her battle against heresy.
In view of the stress laid upon the necessity of membership of the Church for salvation it is understandable that the possibility of salvation for those outside the Church is mentioned only hesitantly. St. Ambrose and St. Augustine admit that catechumens who depart this life before the reception of Baptism can win salvation on the ground of their faith, their desire for Baptism, and their internal conversion (St. Ambrose, De obitu Val. 51; St. Augustine, De hapt. IV 22,29). On the other hand, Gennadius of Marseilles denies them this possibility, except in the case of martyrdom (De eccl. Dogm. 74). St. Augustine distinguishes also, not indeed using the terminology, between material and formal heretics. Thus he does regard material heretics as heretics properly so-called (Ep. 43, I, I). He seems to estimate their possibility of salvation otherwise than he does that of heretics proper.