It should be noted that the Church has been engaging with and teaching against the contraceptive actions of the world for centuries. It is not a modern times reaction on behalf of the Church, for there have been sinful methods to prevent pregnancy and new life since ancient times. The traditional unilateral teaching of orthodox bishops and saints throughout Church History has always been against these contraceptive mentalities and methods.
And before reading these quotations from some within the Early Church, as Catholic Answers states "it should be noted that some of the Church Fathers use language that can suggest to modern ears that there is no unitive aspect to marital intercourse and that there is only a procreative aspect. It is unclear whether this is what some of them actually thought or whether they are intending simply to stress that sexual activity becomes immoral if the procreative aspect of a given marital act is deliberately frustrated. However that may be, over the course of time the Church has called greater attention to the unitive aspect of marital intercourse, yet it remains true that the procreative aspect of each particular marital act must not be frustrated.
St. Clement of Alexandria (The Instructor of Children 2:10:91:2; 2:10:95:3 [A.D. 191]):
“Because of its divine institution for the propagation of man, the seed is not to be vainly ejaculated, nor is it to be damaged, nor is it to be wasted [...] To have coitus other than to procreate children is to do injury to nature”
St. Augustine of Hippo:
“You [Manicheans] make your auditors adulterers of their wives when they take care lest the women with whom they copulate conceive. They take wives according to the laws of matrimony by tablets announcing that the marriage is contracted to procreate children; and then, fearing because of your law [against childbearing] . . . they copulate in a shameful union only to satisfy lust for their wives. They are unwilling to have children, on whose account alone marriages are made. How is it, then, that you are not those prohibiting marriage, as the apostle predicted of you so long ago [1 Tim. 4:1–4], when you try to take from marriage what marriage is? When this is taken away, husbands are shameful lovers, wives are harlots, bridal chambers are brothels, fathers-in-law are pimps” (Against Faustus 15:7 [A.D. 400])
“I am supposing, then, although you are not lying [with your wife] for the sake of procreating offspring, you are not for the sake of lust obstructing their procreation by an evil prayer or an evil deed. Those who do this, although they are called husband and wife, are not; nor do they retain any reality of marriage, but with a respectable name cover a shame. Sometimes this lustful cruelty, or cruel lust, comes to this, that they even procure poisons of sterility. . . . Assuredly if both husband and wife are like this, they are not married, and if they were like this from the beginning they come together not joined in matrimony but in seduction. If both are not like this, I dare to say that either the wife is in a fashion the harlot of her husband or he is an adulterer with his own wife” (Marriage and Concupiscence 1:15:17 [A.D. 419]).
St. John Chrysostom "Homilies on Matthew 28:5" [A.D. 391]:
“[I]n truth, all men know that they who are under the power of this disease [the sin of covetousness] are wearied even of their father’s old age [wishing him to die so they can inherit]; and that which is sweet, and universally desirable, the having of children, they esteem grievous and unwelcome. Many at least with this view have even paid money to be childless, and have mutilated nature, not only killing the newborn, but even acting to prevent their beginning to live”
Caesarius of Arles "Sermons" 1:12 [A.D. 522]
“Who is he who cannot warn that no woman may take a potion so that she is unable to conceive or condemns in herself the nature which God willed to be fecund? As often as she could have conceived or given birth, of that many homicides she will be held guilty, and, unless she undergoes suitable penance, she will be damned by eternal death in hell. If a woman does not wish to have children, let her enter into a religious agreement with her husband; for chastity is the sole sterility of a Christian woman”
St. Epiphanius of Salamis "Medicine Chest Against Heresies" 26:5:2 [A.D. 375]:
“They [certain Egyptian heretics] exercise genital acts, yet prevent the conceiving of children. Not in order to produce offspring, but to satisfy lust, are they eager for corruption”
The traditional teaching of condemning the use of contraception was so prevalent throughout the history of Christian thought and theology that this belief was carried on by Protestants as well up until the 20th century. Some of the Reformers had this to say on the matter:
"Onan must have been a malicious and incorrigible scoundrel. This is a most disgraceful sin. It is far more atrocious than incest and adultery. We call it unchastity, yes, a sodomitic sin. For Onan goes in to her; that is, he lies with her and copulates, and when it comes to the point of insemination, spills the semen, lest the woman conceive. Surely at such a time the order of nature established by God in procreation should be followed. Accordingly, it was a most disgraceful crime to produce semen and excite the woman, and to frustrate her at that very moment. He was inflamed with the basest spite and hatred. Therefore he did not allow himself to be compelled to bear that intolerable slavery. Consequently, he deserved to be killed by God. He committed an evil deed. Therefore God punished him."
“I will content myself with briefly mentioning this, as far as the sense of shame allows to discuss it. It is a horrible thing to pour out seed besides the intercourse of man and woman. Deliberately avoiding the intercourse, so that the seed drops on the ground, is doubly horrible. For this means that one quenches the hope of his family, and kills the son, which could be expected, before he is born.
The wickedness is now as severely as is possible condemned by the Spirit, through Moses, that Onan, as it were, through a violent and untimely birth, tore away the see of his brother out the womb, and as cruel and shamefully was thrown on the earth. Moreover he thus has, as much as was in his power, tried to destroy a part of the human race. When a woman in some way drives away the seed out the womb, through aids, then this is rightly seen as an unforgivable crime*. Onan was guilty of a similar crime, by defiling the earth was his seed, so that Tamar would not receive a future inheritor.” – (Commentary on Genesis)
“Onan, though he consented to marry the widow, yet to the great abuse of his own body, of the wife he had married and the memory of his brother that was gone, refused to raise up seed unto the brother. Those sins that dishonour the body are very displeasing to God, and the evidence of vile affections. Observe, the thing which he did displeased the Lord – And it is to be feared, thousands, especially single persons, by this very thing, still displease the Lord, and destroy their own souls.” - (Notes on the First Book of Moses, comment on 38:7)
The fact that Christians of differing denominations had unanimous agreement on the sinful nature of contraception and its varying forms until this last century shows to the extent that society has pressured many Believers to succumb to the contraceptive mentalities of the world. How many Believers nowadays dare to hold to the centuries old moral Biblical teachings?
The Church does promote the physical unitive quality of marriage, and encourages the beauty of such a unity to flourish and thrive in the love of God and love of another. For this very reason, it teaches as it does so that couples of good-will do not act contraryto God's Will for the human design and purpose. So we should never detract from the absolute gravity of such acts against procreation in any which way, for they are, in turn, acts against love and life, and in turn acts against God. Our Lord gave us natural abilities by which we get to participate with Him in Creation, in carrying on the human race that He designed in His Image. It truly is a gift and a privilege that we should not hinder but embrace full heartedly with no lack of Faith in Our Lord and Our God, who is Love, and Creator of all things good.