1. Because they do not love God and neighbour.
They only have lust one for the other; and this prevents them from rising up to the love of a spiritual being like God. Let us look at a spiritual principle. It states; one who does not progress will regress.
Everyone is born in the natural level. Though they have a spiritual soul, that is part of the natural state of man.
Because of 'original sin' man tends to descend from the natural level down to the unnatural level. And continues to descend to the level of perversion or bestial level. This is a natural tendency for all men in the state of original sin.
So Christ came to teach man to do otherwise; i.e. to rise up continuously from the natural level to the supernatural level. Baptism is supposed to do that but it often does not work due to lack of proper disposition.
To ascend is possible only through the help of Divine Grace which Christ earned for mankind with His death. Each soul can receive this grace that will enable him to ascend to the supernatural level through the 'plan of salvation' taught by Christ and found in Divine Revelation, and elaborated by the Fathers of the Church.
So, it is either up or down. When a soul stops ascending, he automatically descends. When he stops descending, he does not rise up; he continues to descend. In the spiritual life, no one has a choice; he must continuously rise up to the supernatural level with the help of God's grace, otherwise he will descend.
This is the reason why many souls have descended to the unnatural level and have become homos; because they do not used what will make them ascend, the 'love of God and neighbour,' which can only be done with the help of the grace of God.
2. The soul ascends to the supernatural level with the help of the grace that enables him to Love God and neighbour.
This is taught to all through the Liturgy of the Mass, specifically in the Sunday Gospels and its interpretation from the Fathers of the Church.
Rising to the supernatural level consist is these steps;
First, the soul must have perfect repentance.
Secondly, the soul must begin to believe. This belief must be perfected following the lessons learned through the Sunday Liturgy.
Thirdly, having perfected one's Faith by believing that Christ is Man and God, the soul begins to attain the beginnings of Charity.
Upon attaining from God the beginnings of the theological virtue of Charity, the soul is in the supernatural level.
3. The third stage in the spiritual life is what seminarians, priests and bishops did not undergo.This is the reason they descended into unnatural sins and bestiality. God does not love them.
The first stage of the spiritual life is obedience to the command of Christ 'to repent.' The second stage of the spiritual life is obedience to the command of Christ 'to believe.' The third stage of the spiritual life is obedience to the 'new commandment of Christ' which is 'love one another as I have loved you.'
4. 'As I have loved you.'
Man knows how a husband loves his wife and vice versa. Man knows how parents love children. But no man knows how God loved man. Only God knows how He loved man. And God knows no one knows how God loved man so how can man love God and neighbour as God loved man? No way, unless God loves man first.
God decided to love man first. And learning from this, man may love God and neighbour the way God had loved him first.
Then St. Thomas of Aquinas reminded us that God does not love us because we are good. The other way around. We become good because God loved us. It is God's love for man that makes man holy.
Then man, having been loved by God first, can now love God and neighbour. And in loving his neighbour, man can make his neighbour good with the help of God.
So the sequence must be clear. God loves man first. This love makes man good. And when man, loved by God, loves his neighbour, this makes his neighbour good.
See how God's love for man solves all the above problems.
5. The problem.
But God loves only the humble and hates the proud, Scriptures has it. So to be loved by God and receive all the benefits from that love we have to be humble as Christ commanded; 'learn from Me for I am meek and humble of heart.'
So the entire Catholic spirituality which have been lacking in all seminaries and religious houses is the training in humility which should be the only training in spirituality. Christ said so. He did not say learn theology. He said; 'learn from Me.' What? 'Meekness and humility.'
6. The world is proud.
Christ prophesied, the world will be filled with the pride of life that will cause the decay of Faith and the waxing cold of Charity. Christ said so. And the world is filled with all kinds of pride explained by St. Pope Gregory the Great. Being proud, God does not love the people in the world. He hates them. Thus the people in the world cannot be good. This is why most of the pagans in the world, most of the Protestants and most of the Catholic bishops and priests are homos. Because of their pride, God hates them. So God permitted them to descend to the unnatural level and even hit the bottom, the beastial level. In such a situation there was no stopping this lustful trend.