If you want to model your life after someone, then you need to leave behind other things. It’s basic computation. If you want to adopt a healthy diet, you have to leave behind certain foods. If you want to emulate a skilled athlete, you have to unlearn, or leave behind, your old ways of training.
When someone comes to faith in Jesus from a family or community environments that is hostile to the gospel, he quickly finds out what and who he must leave behind. Many are forced to leave their families, or shunned by their community of origin. Take for example, Steven Masood, who was shunned by his family and fled Pakistan after becoming a Christian as a teenager.
But for may of us who grew up around Christianity, the category of “what we need to leave behind in order to follow Jesus” may seem like a very short list, or some behavior we were not very likely to participate in anyway. Deitrich Bonhoeffer in his classic book The Cost of Discipleship, wrote that the Lutherans had “gathered like eagles round the carcase of cheap grace, and there we have drunk of the poison which has killed the life of following Christ”. (pg. 53)
Following Christ has huge implications. Jesus is not your Lord if He does not change your heart attitudes and your actions in significant ways. In order to follow Christ we need to leave behind the things that we previously thought we could not live without: people approval, worldly success, materialism, the idolatry of sex or relationships, human pride, etc. But taking up one’s cross and following Jesus is the beginning of community with our Lord, not the end. When leave behind the things Jesus asks us to give up, we find new treasures and satisfactions awaiting us.