All too often Christianity is cheapened to the point that it becomes a religion of rules in which the do's and don'ts (especially the don'ts) govern our lives. In an effort to please God by keeping ourselves separate from the world (2 Cor 6:17), we live lives that are unattractive, to say the least, to those who don't know Jesus. When our spiritual walk is governed by obligation and duty and law (this is what I ought to do, this is how good Christians behave) it leads to a lifeless religion based on rules and regulations.
Most people in the West were brought up in a shame-based religion. "People are dying and going to hell. Therefore you should preach the Gospel." Although it sounds spiritual, the reasoning is guilt-based. It implies, "Christ died for your sins and you are doing so little for him. You are guilty. You ought to be doing more." It attempts to shame us into different behavior.
The letter of the law kills, but the Spirit gives life!
What motivates us is important. The grace and love of Jesus operating inside us cause us to want to do what legalism says we ought to do.