I think there is an unfortunate tendency in the modern American church to focus on only one half of the Gospel message. Now, the interesting thing is that different churches tend to pick different halves.
The Gospel can be summed up like this: You, like everyone else are a sinner and have destroyed any chances of getting into heaven by all of the bad stuff you've done, we call this "sin." Because of that, you have chosen hell as your final destination. However, God is unwilling to let you go there without a chance for redemption. Thus, he sent his Son Jesus Christ two millenia ago to show humanity what a perfect life looks like and then to give up that perfect life in a sacrifice to satisfy the punishment you (and all others) should endure. He then rose from the dead to prove his conquest over death and that there is hope to have life. To gain this life, you must believe in Christ and his sacrifice and ask him to forgive you for your sins. Once done, your destiny is switched from eternal damnation to eternal paradise. Your mind is freed from the slavery to sin, but you must still abide in a corrupt body until death when you too will be reborn into your new body in paradise.
That is the jist of the Gospel. The half Gospel is one of two things: (1) go to hell, you sinners! or (2) oh, it's so happy, we get to go to heaven! These half-gospels come in many forms ranging from bad theology to pure heresy.
In the negative half Gospel, the milder forms usually come out as forms of legalism where Christians forget the freedom brought to us by Christ (read Galatians sometime). Or, we find the hypercritical Christians who consider any deviation from their exacting beliefs to be tantamount to heresy. Again, this forgets the freedom we have in Christ. As Christians, we can still make mistakes and the grace of God covers them over. In cult form, we find the older cults of Mormonism, Jehovah's Witness, or even the Judaizers described in the New Testament. They break Christianity by adding to grace or by so badly twisting the words of the Bible to fit their own agendas and reform the Bible into their own heresies.
In the positive half Gospel, the weaker theology usually comes out as easy-believism (now that God forgave me of my sin, I can do anything fun and sinful and get away with it) or even trying to make the Gospel "relavant" to our culture. Cultural relevance is an especially dangerous trap because it honestly sounds good—and in a small measure, it even is good (Paul talks about this in 1 Corinthians). Yet, in an attempt to make the Gospel "seeker sensitive" or easier to digest, we change it. If you only believe in the happy half of the Gospel, how are you to cope when God puts you to the test? Jesus said that following him would be a light load, but it will lead to hard times. The word of faith movement is a cult example where the Gospel becomes a magic spell to solve all our problems.
The truth is, we must always remember that the Gospel has a dark side and a light side. The dark side is that humanity is nothing but a soiled rag. We have nothing to offer God (he's already God, what would we offer?). We had it all and we tossed it aside so we could do things our way. The American revolutionary in me says, "Cool!" But, such rebellion to the God of heaven has consequences, especially when his way was perfect and pain free. Total depravity is something we Christians must never forget and we must broadcast as the fundamental first step to belief. All humans will go to hell if they do not take active steps to change their position with God. Anyone who chooses to reject God's Way, will go to hell. That's final. The New Testament couldn't be any clearer.
On the other hand, we must also remember that God is Love. He wants us to be free. He created us with the ability to think freely and to do freely. He wants us to choose the way we want ourselves and doesn't want to force us into the same mold. We all have the freedom to do what's right in Christ. That may even look different for different people (read first and second Corinthians).
We must remember the humility of the negative. We must remember the joy of the positive. The half Gospel, whether half-empty or half-full, isn't enough.
