If I were to be a Christian, my primary focus couldn't be about the problems of the world, because it would be about God.
For the Christian, the problems of the world all relate back to the their problem with God. Sin separates us from God and as a consequence creates relational problems between man and man.
In fact in Genesis 3, when Adam and Eve first sin, the immediate consequence that follows is that the man and the woman become ashamed of themselves. This sense of shame would clearly create a relational problem between the man and the woman, but it gets worse. The next thing that happens when God appears:
Genesis 3:8 ...the man and his wife hid themselves from the presence of the Lord God among the trees of the garden.
The Hebrew literally reads "the man hid himself and the woman herself." In other words, it's every man for himself. And this point follows through the rest of Scripture (where Adam and Eve's children start to kill each other).
I say all this to make the point that for the Christian the primary focus is about God because in Him we find the solution to man's problems. This doesn't mean that God is a means to an end (peace between men), but that only when God becomes our end (goal) will we also have peace with each other.
In the Christian worldview, these two things go hand in hand. You don't have one without the other. This is why 1 John 4:20 says "If anyone says, 'I love God,' and hates his brother, he is a liar; for he who does not love his brother whom he has seen cannot love God whom he has not seen." And Matthew 22:36–37 says “'Teacher, which is the great commandment in the Law?' And 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.'"
The love of God is more foundational, but part of its very nature is to love others too. So having God as our primary focus is how we make the world a better place.
Every good action I do was part of God's plan, all my sins can be indirectly led back to the devil. With atheism, I know that what I've done was through my own doing, and it makes it so that I have to take responsibility.
Again, to clarify the Christian worldview on this issue: Scripture is clear that no one can blame the devil for their sins. Matthew 12:34–35 says, "...For out of the abundance of the heart the mouth speaks. The good person out of his good treasure brings forth good, and the evil person out of his evil treasure brings forth evil."
It's true that a lot of Christians today try to blame a lot of stuff on Satan… And Christians also get confused and think that their thoughts are God's thoughts. In fact I recently got into a debate with some people on this website over this very issue. My concern was basically exactly what you've said: these people start getting confused as to which thoughts are their own. They never know whether a thought they are thinking is their thought, God's thought, or Satan's thought! This hinders their growth in taking responsibility for their own ideas and, consequently, actions. Personally, I find it ridiculous… But my point is that if Christianity is going to be found wanting, we need to make sure that what we are finding fault with is actually Christianity and not some person's distortion of it. It would be a shame if someone rejected Euclid's geometry simply because his Math teacher in high school explained it wrongly to him.
when I see truth, what have I to loose?
Nothing. Nothing to lose, nothing to gain
