When talking with a Christian, the first concept non-Christians encounter, that they don't understand, is sin. Sin simply means doing something evil or morally wrong. Surprisingly, most major belief systems have a similar set of offenses, they consider morally wrong. Examples of sin, included: committing adultery, stealing (or pirating), lying, not obeying parents, and murder. Some of these are also illegal, while others are not.
Many more people have heard of karma, which is an Indian (from India) concept, in origin, which appears, in all forms of Indian belief systems. Karma and sin are both about right and wrong, but karma comes out of a lack of knowledge, and the cause of sin is an act of the will (a choice), while karma is remedied by discipline, and sin can be remedied God's grace and our repentance.
When non-Christians claim they respect Jesus Christ, they find instances of Christ showing love and non-condemnation, but they refuse to acknowledge that Christ is the perfectly good and completely just Ruler of the multi-verse, as well. God has a set of moral standards, by virtue of being perfectly good. We have chosen, to do evil, by breaking God's laws and hence brought suffering into our world, families, and spiritual selves.
In order to resolve this evil, God sent Himself, as Jesus Christ, to suffer the penalty, for our sins. This penalty is physical and spiritual death and Christ defeated this by His living a perfectly good life, dying painfully on the cross, descending to hell, and defeating the devil. Afterwards, Jesus Christ came back to earth and, after showing all His followers proof of His resurrection, eventually ascended to Heaven.
So, while God is perfectly loving, there is much more to Him, and He was so serious about sin, that He dealt with it by suffering Himself, on our behalf. We hear a lot about the devil, but the real battle is within our own souls. The devil is here, to make things worse, but he has no power, compared to God. The devil cannot force you to do anything you do not want to do and cannot harass born-again Christians.
The way to guarantee, that you will go to the Christian heaven, is to ask God for forgiveness, of your sins and believe that God raised Jesus from the dead, after He died, on the cross, for our sins. Then you commit your life, to following God, rather than your desires. This is just the first step, in the journey. You will find the rest of the instructions, in the Bible.
Being a Christian has its ups and downs, as any life does and Christians do suffer and die. The difference is that we have an appreciation, of the spiritual world and peace and hope, that things really will work out in the end. Christ intervenes, at times, when we really need Him.
Much of our Christian lives involves doing routine work and doing what is needed to stay healthy, but our focus is on helping others and improving our lives, as we gradually give God control more and more of our lives. But we have a quiet assurance, that our lives mean something and that no matter what we have to live through, after we die, we will live forever in paradise, and are guaranteed to live forever without pain.
The hardest part, for non-believers, to accept about Christianity is that they need to give control of their lives to God. That is why the world will never understand or accept us or our way of life. They think they are in control and we are the drones, but we know better. You either can be a slave, to your own desires, or you can conquer them, but you need help.
We have already tried things our way and look at the way the world turned out. We even know now that all those "Angry God" judgements God has laid on us for our sins were entirely caused directly by our own gluttony and selfishness, also known as, environmental disasters and global warming/climate change. Isn't it time we give God a turn.
Following God is not like following orders, from a Sergeant, in the military. God rarely speaks to us, in a vision and gives us detailed instructions, on some special mission. God is less interested in what you do for a living, then who you are as a person. God wants you to not only to live a better life but a happier one too. God desires His followers, to think critically, before following what they think God says and compare it, to what God has done in the Bible.
Following God is also not the same as following a particular church or member of the clergy. People make mistakes and bad choices - Christians as well. Even well meaning Christians can cause a lot of damage, because they have a poor understanding of Scripture and who God is.
There is a large minority of Christians - often older respected members of the Church - who will make you feel like you have to choose between living a happy life and being a Christian. This is the opposite of what God has in mind. Christianity is there to restore your free will and improve your life and how you see it. Anything that contradicts that is not of God.