Mahammad-
From the examples you've given I suspect that you have witnessed Christianity and the cross being used as a manipulative device rather than being honestly portrayed. We do have some churches on the radical end of Christianity, as well as some sects, which give Christ lip-service while demanding that we accept their theologies in order to merit salvation.
In some cases their tactic is to get their laity so focussed on condemning a certain group of people, such as gays or muslims, that they don't realize what the heirarchy is actually up to, namely, cementing their own power. Rather than teaching their members that it is only God himself to whom we must answer, they persuade the people through chicanery, bullying and intimidation that it is the heirarchy itself that must be answered to. They attempt to reduce God to the status of a religious icon supporting whatever belief system that they have contrived.
As for what Christians are to approve of, what we are to reject, and the limits within which all our actions are to be contained, here is the 'condensed version', taken directly from Scripture:
So I say, live by the Spirit, and you will not gratify the desires of the sinful nature. For the sinful nature desires what is contrary to the Spirit, and the Spirit what is contrary to the sinful nature. They are in conflict with each other, so that you do not do what you want. But if you are led by the Spirit, you are not under law.
The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God.
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control. Against such things there is no law. Those who belong to Christ Jesus have crucified the sinful nature with its passions and desires. Since we live by the Spirit, let us keep in step with the Spirit. Let us not become conceited, provoking and envying each other. (Galatians 5:16-26,NIV)
We as Christians recognize this as our code of conduct. Those feelings and actions which are listed in paragraph #2 are indications of the sinful nature still trying to wreak havoc.
But it is not enough for us to shun the acts of the sinful nature. Our actions, and even our reactions, must conform to 'the fruit of the Spirit', listed in paragraph #3. Every feeling, every thought, and every action that we as Christians have or perform is to have as its root those 'fruits'. When the feelings, thoughts and actions go outside those borders, when they fail to fit inside those parameters, we have 'backslid' to the sinful nature.
There are no exceptions to this. As Christians we firmly believe that we have the help and guidance of the Holy Spirit. It is he who brings with him the fruits we see listed in paragraph #3. It is he who battles our sinful nature, subdues it for us, and replaces it with his fruits. So what God himself has seen fit to instill in us (the fruits), thereby quite literally creating in us a new heart, we are to welcome into our lives. And then our lives are to reflect those fruits.