This is a very challenging question. I think speaking to Christians who are not fully grasping the entirety of the Christian message is very frustrating for friends looking on. The fruits of the spirit mentioned in Galatians 5:22-23 should be evident in an individuals life. In other words, one should act like Christ. James makes it very clear that our words and actions should match. Saying that one is a follower of Jesus should also mean that they look like they are following Jesus.
So, in regards to your question, the way I deal with this situation is to continue to grow in my relationship with the Lord and let them watch. I don’t think it is always beneficial to be calling and encouraging people to be more like Christ that don’t want to be themselves. Once I get the vibe that they want to live how they want, I make a mental note and the nature of our relationship changes a bit in my mind. While I grieve for their decision, I think preservation of the relationship becomes very important because if/when they get to a point where they want to take things more seriously with God, I want to be someone they can come to with questions. And so, I sit back and let people form their own relationship and walk with God. Now, I’m assuming here that these are people who know that Jesus wants more from them then what they are offering. As opposed to someone who is completely clueless as to what God wants from them.
In fact, this just happened to me recently, where someone I have known for 20 years is at a place where they are really ready to wrestle through how they know Christianity is true, or how Christians know our God is the true and right God etc. Now, they would have called themselves a Christian all these past years, but they may also have acknowledged that they were doing average in their relationship and there’s things they should be doing better than what they were doing previously. However, they have been watching some documentaries on TV and that is making them question everything. They are now at a place where all they want is truth and to not just follow something because this is always something they did, or because they grew up going to church. In other words, they are ready to take this whole faith things seriously. But the reality of this situation is that they had to come to that place on their own. Had I said things over the years more strongly than the bits I offered them, they would have just rejected me all together. While I don’t mind being rejected for Christ, this would have been different because the impact on where she is now would have changed. See, because I was able to preserve the relationship, she now wants me to be a part of her journey of asking questions and finding truth.
All that said, our relationship over the last several years consisted of me sharing with her about my life and what I was doing in ministry (and life in general) and her sharing with me what was going on with her. Our relationship continued to grow and now that she is at the place she is at, we are moving on to this particular place in our relationship-- finding truth.
So, perhaps what you could do is continue to pray for them, and allow them to silently observe your life as a Christian fully devoted to God. Be there for when they want to talk. Always keep in mind that everyone’s path to spiritual maturity is different, but we always want people to get it right with God now before something tragic happens! But one thing I’ve learned in my 6+ years of doing Apologetics with RZIM, is that you can’t make anyone believe or serve God. As difficult this stage is, I would rather them go through the maturity stages with you than without! Thank you for loving your friends!