Many scientists are justifiably scandalized by Christian Fundamentalists' assertion that the world had to have begun ~10,000 years ago and that it only took six 24-hour periods to come into existence. This assertion is wrong in two respects: (a) The Hebrew word םוי ("yom") in Genesis can either mean a 24-hour period or an indefinite length of time, and (b) if God did stop creating the universe after six days, it would no longer exist today; this is because God creates with creatio ex nihilo ("creation out of nothing"), creation in its true sense and proper only to God, Who sustains everything in existence. So these Fundamentalists have an incorrect understanding both of the literal sense of Genesis and of creation.
Dr. Ludwig Ott summarizes the Catholic perspective, which opposes that of Fundamentalist Christians, in his Fundamentals of Catholic Dogma (pp. 93-94):
The Divine Work of Creation
Revealed Doctrine concerning Material Things, i.e., Christian Cosmology
§ 11. The Biblical Hexahemeron (The Six Days of Creation)
1. General Principles
In order to solve the difficulties deriving from the apparent contradiction between the results of natural science and the Biblical narrative of the Creation the following general principles are to be observed:
a) Even though all Holy Writ is inspired and is the Word of God, still, following St. Thomas (Sent. II d. 12 q. 1 a. 2), a distinction must be made between that which is inspired per se, and that which is inspired per accidens. As the truths of Revelation laid down in Holy Writ are designed to serve the end of religious and moral teaching, inspiration per se extends only to the religious and moral truths. The profane facts of natural science and history contained in Holy Writ are not inspired per se, but only per accidens, that is, by virtue of their relation to the religious-moral truths. The data inspired per accidens is also the Word of God, and consequently without error. However, as the hagiographers in profane things make use of a popular, that is, a non-scientific form of exposition suitable to the mental perception of their times, a more liberal interpretation, is possible here. The Church gives no positive decisions in regard to purely scientific questions, but limits itself to rejecting errors which endanger faith. Further, in these scientific matters there is no value in a consensus of the Fathers since they are not here acting as witnesses of the Faith, but merely as private scientists.
b) Since the findings of reason and the supernatural knowledge of Faith go back to the same source, namely to God, there can never be a real contradiction between the certain discoveries of the profane sciences and the Word of God properly understood. The Vatican Council declared: Nulla unquam inter fidem et rationem vera dissensio esse potest. D 1797.
2. Decisions of the Bible Commission (30/6/1909)
a) The first three Chapters of Genesis contain narratives of real events (rerum vere gestarum narrationes quae scilicet obiectivae realitati et historicae veritati respondeant), no myths, no mere allegories or symbols of religious truths, no legends. D 2122.
b) In regard to those facts, which touch the foundations of the Christian religion (quae christianae religionis fundamenta attingunt), the literal historical sense is to be adhered to. Such facts are, inter alia, the creation of all things by God in the beginning of time, and the special creation of humanity. D 2123.
c) It is not necessary to understand all individual words and sentences in the literal sense (sensu proprio). Passages which are variously interpreted by the Fathers and by theologians, may be interpreted according to one’s own judgment with the reservation, however, that one submits one’s judgment to the decision of the Church, and to the dictates of the Faith. D 2124 et seq.
d) As the Sacred Writer had not the intention of representing with scientific accuracy the intrinsic constitution of things, and the sequence of the works of creation but of communicating knowledge in a popular way suitable to the idiom and to the pre-scientific development of his time, the account is not to be regarded or measured as if it were couched in language which is strictly scientific (proprietas scientifici sermonis). D 2127.
e) The word “day” need not be taken in the literal sense of a natural day of 24 hours, but can also be understood in the improper sense of a longer space of time. D 2128. Cf. the whole letter of the Secretary of the Bible Commission to Cardinal Suhard, dated 16th January, 1948 (D 3002).
3. Explanation of the Work of the Six Days
The Biblical account of the duration and order of Creation is merely a literary clothing of the religious truth that the whole world was called into existence by the creative word of God. The Sacred Writer utilised for this purpose the pre-scientific picture of the world existing at the time. The numeral six of the days of the Creation is to be understood as an anthropomorphism. God’s work of creation represented in schematic form (opus distinctionis—opus ornatus) by the picture of a human working week, the termination of the work by the picture of the Sabbath rest. The purpose of this literary device is to manifest Divine approval of the working week and the Sabbath rest. Cf. Ex. 20:8 et seq.
The many theories which have been evolved to explain the Biblical Hexahemeron (the six days of Creation), fall into two groups. The former regard Gn. 1, as giving a historical account of the duration and sequence of the works of creation (realistic theories). The second group sacrifices the historicity of the narrative concerning the duration and sequence of the works of the Creation, and in order to avoid conflict with natural science, assumes that the division of the six working days derives from the imagination of the Sacred Writers (idealistic theories). To the former group belong those who hold the “Verbal Theory,” which is expounded by most of the Fathers and Schoolmen, the “Restitution Theory,” the “Sin Flood Theory,” and the various “Concordance Theories,” which explain the six days of Creation as six periods of creation. To the second group belong the “Allegorism of St. Augustine,” “The Vision Theory,” “Poetism,” “The Anthropomorphistic Explanation,” mentioned above, and “Mythism,” which has been rejected by the Church (D 2122).
§ 12. The Doctrine of Evolution in the Light of the Revelation
1. The materialist doctrine of evolution (E. Haeckel) which assumes the eternal existence of uncreated material, and which explains the emergence of all living creatures, of plants and animals and also of men, both body and soul, through purely mechanical evolution out of this material, is contrary to Revelation, which teaches the creation of the material and its formation by God in time.
2. The doctrine of evolution based on the theistic conception of the world, which traces matter and life to God’s causality and assumes that organic being, developed from originally created seed-powers (St. Augustine) or from stemforms (doctrine of descent), according to God’s plan, is compatible with the doctrine of Revelation. However, as regards man, a special creation by God is demanded, which must extend at least to the spiritual soul (creatio hominis peculiaris D 2123). Individual Fathers, especially St. Augustine, accepted a certain development of living creatures. Proceeding from the assumption that God created everything at the one time (cf. Ecclus. 18:1), they taught that God brought a certain part of His creatures into existence in a finished state, while He created others in the form of primitive seeds (rationes, seminales or causales) from which they were gradually to develop. Those Fathers and Schoolmen who accepted a development, conceived a development of the individual species of living things each from a particular primitive form created by God; but modern theories of evolution (descendence theory) conceives the development as from one species to another. According as these give priority to evolution from a plurality of original forms or from one single stem-form (primitive form) one speaks of a many-stemmed (polyphyletic) or single-stemmed (monophyletic) development. From the standpoint of the doctrine of evolution, either form is possible. From the standpoint of natural science, F. Birkner says: “A single-stemmed monophyletic development of living beings is to be rejected, as the transitions from one group to the other are missing. Everything seems to favour a many-stemmed, polyphyletic development. Unfortunately, up to the present it has not been possible to determine how many primitive forms or basic organisations of living beings existed.”