… the Church most definitely does not teach that Catholics are supposed to be against capital punshiment in all cases.
Here is what the USA Catholic bishops teach: They explicitly call for the abolition of capital punishment:
“CHRISTIAN VALUES IN THE ABOLITION OF CAPITAL PUNISHMENT
We maintain that abolition of the death penalty would promote values that are important to us as citizens and as Christians. First, abolition sends a message that we can break the cycle of violence, that we need not take life for life, that we can envisage more humane and more hopeful and effective responses to the growth of violent crime. It is a manifestation of our freedom as moral persons striving for a just society. It is also a challenge to us as a people to find ways of dealing with criminals that manifest intelligence and compassion rather than power and vengeance. We should feel such confidence in our civic order that we use no more force against those who violate it than is actually required.
Second, abolition of capital punishment is also a manifestation of our belief in the unique worth and dignity of each person from the moment of conception, a creature made in the image and likeness of God. It is particularly important in the context of our times that this belief be affirmed with regard to those who have failed or whose lives have been distorted by suffering or hatred; even in the case of those who by their actions have failed to respect the dignity and rights of others. It is the recognition of the dignity of all human beings that has impelled the Church to minister the needs of the outcast and the rejected and that should make us unwilling to treat the lives of even those who have taken human life as expendable or as a means to some further end.
Third, abolition of the death penalty is further testimony to our conviction, a conviction which we share with the Judaic and Islamic traditions, that God is indeed the Lord of life. It is a testimony which removes a certain ambiguity which might otherwise affect the witness that we wish to give to the sanctity of human life in all its stages. We do not wish to equate the situation of criminals convicted of capital offenses with the condition of the innocent unborn or of the defenseless aged or infirm, but we do believe that the defense of life is strengthened by eliminating exercise of a judicial authorization to take human life.
Fourth, we believe that abolition of the death penalty is most consonant with the example of Jesus, who both taught and practiced the forgiveness of injustice and who came “to give his life as a ransom for many.” (Mark 10:45) In this regard we may point to the reluctance which those early Christians who accepted capital punishment as a legitimate practice in civil society felt about the participation of Christians in such an institution(3) and to the unwillingness of the Church to accept into the ranks of its ministers those who had been involved in the infliction of capital punishment.(4) There is and has been a certain sense that even in those cases where serious justifications can be offered for the necessity of taking life, those who are identified in a special way with Christ should refrain from taking life. We believe that this should be taken as an indication of the deeper desires of the Church as it responds to the story of God’s redemptive and forgiving love as manifest in the life of his Son.”
So at one time, the Church taught in favor of burning heretics at the stake, while at another time the Church teaches in favor of the abolition of capital punishment. Does this not indicate that morality is relative and subjective to the times and culture?