Why would we have a problem cutting down a tree?
Life is so confusing when you choose to ignore reality.
Try this out:
1. God exists, and He has revealed Himself through His prophets and apostles.
2. God has told us He has given us this planet for our use, and that we are to multiply and fill the Earth.
3. After the Flood, God gave specific permission to mankind to eat animals for food.
4. This same God reminds us that a righteous person, someone that is concerned about what God thinks, treats his animals with mercy. Admittedly, many slaughterhouses do not concern themselves with this. But then, those running them likely do not care what God says.
5. God created mankind in His image, He creates each and every one of us, therefore we have built-in, God given worth.
6. God has told us that if one person murders another, that person is to be killed (not murdered) for this offense against God.
7. There are two genders- male and female. For those who like to whine about the unfortunate mutations (a result of man's fall, and the resulting curse on creation), they can only whine about them because these mutations are recognizable as falling outside the norm.
8. Etc.
This isn't as hard when you lay aside a transitive morality, or a morality dictated by some alleged majority, that is ever-shifting and unsupportable by reality.