Saying Friedrich Nietzsche was critical of Christianity might be a slight understatement. He thought it was an oppressive, mendacious, and all around sick religion that put people in bondage essentially. Nietzsche's notion of master and slave morality in On The Genealogy of Morality was a legendary and devastating critique of Christianity. With Christianity's emphasis on empathy, compassion, and pity as actually a veiled notion of resentment, it seemed that Christianity was busted for being nothing more than an upside down power move to bring down the class of people on top of society and bring up the people on bottom of society. Nietzsche thought that what controls us is not so much the coercive force of other people but the values and morality of Christianity that govern society. Instead of directly lashing out at the person who hurt you, like in master morality someone would do, slave morality demands that we "turn the other cheek." Slave morality demands that we pity our enemies and show them compassion even when they are malicious and cruel. Nietzsche thought this was an inversion of healthy and strong values and that this ultimately embodied resentment.
Its oddly interesting that as someone who considers himself to be a Christian and someone who loves Nietzsche, these contradictory impulses and likes would cause me to have a lot of cognitive dissonance. Firstly though, I agree with Nietzsche that often slave morality can make people "sick." Slave morality turns people inward, makes them hesitant and second guess themselves, and ultimately full of resentment. Slave morality does give people a soul though as Nietzsche thought but that comes at a very heavy cost. We are a people in bondage to our values, and as the 20th century philosopher Foucault wrote the mechanism of control in society has moved "from the body to the soul." We are simple put not free as a culture of people in Christendom. So with all this said and at times it certainly being hard to reconcile these two belief systems in Nietzsche's ubermensch values and Christian pity and empathy, I think Nietzsche missed something in his critique of Christianity.
In western Christian Protestant theology, "grace" is the freely given given gift from God for the forgiveness of sins. Grace is the unconditional love that no matter what we do as humans we are forgiven and that God loves us. So if everything is forgiven, then everything is also permissible. I don't think this is license for us to go out and act grossly immoral, but "grace" does also give us back our freedom. Jesus said in Matthew 22: 37-40, "He said to him, “‘You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.’ 38 This is the greatest and first commandment. 39 And a second is like it: ‘You shall love your neighbor as yourself.’ 40 On these two commandments hang all the law and the prophets.” A Christianity that emphasizes love and grace allows us to be free. Much of Christianity has turned into a rule bound religion, that judges anyone it deems to be a sinner very harshly. Christianity has a long and dark history towards anyone that it deems to be in an out-group, but there is another side to Christianity. A Christianity that emphasizes love as love and not an upside down power move that is actually resentment, can free us. Forgiveness and grace is what makes us free. Jesus said in Matthew 18: 21-22, "then Peter came up and said to him, 'Lord how often shall my brother sin against me, and I forgive him? As many as seven times?' Jesus said to him, I do not say to you seven times, but seventy times seven.'" In conclusion Nietzsche just forgot that Christian grace and forgiveness can make us free too. Thank you.