Many new converts lack discipleship because they were not told that they have to accept Jesus lordship in their lives. His lordship over their lives will always produce some sacrifices. Just as Jesus carried His cross to the place of crucifixion, each new convert must be willing to take up his/her own cross and be prepared to die to the desires of his fallen sinful nature, and to the past desires of the sinful pleasures of this world. Even if the Christian's discipleship does not lead to a physical death (martyrdom), it will involve a certain amount of hardship, suffering, and persecution. People who rattle off a sinner's prayer, must be properly mentored, (discipled) and told from the get go what it will cost them to be Jesus' disciples. They must be prepared to live a lifetime commitment to Jesus which involves being a continual learner and doer of God's word. To put their responsibilities to Christ before all other responsibilities, and to be wholehearted in their devotion and worship to the Lord Jesus Christ. There is no place for those who make a start and then give up.
With that said, let me add a few more thoughts here. Pentecostalism came out of the holiness movement of a century and a half ago, and was known for it's holiness "do's and don'ts" (some may shout legalism) but the fact remains, you will rarely hear a sermon on holiness these days. Much of the modern church's emphasis is on conversions and church growth rather than on discipleship. Much of the western mega church's ambition is all about converts and getting people to say a sinners prayer. I can teach a parrot to recite the sinners prayer. That doesn't mean the parrot is a Christian.
Someone may be hollering right about now, "What's your point Smitty?" We've moved away from discipleship, and as a result, we no longer see people thinking and behaving the right way (godly living). That leads to the real question. How are new converts living six months, a year or two after they recited the sinners prayer? What's their current behavior? Are they producing fruit worthy of repentance?
Another definition of discipleship could mean teaching and modeling how to live a life set apart from the secular, godless culture. That set-apart life is what we used to call "holiness." "Be holy, for I am holy," the Bible says in 1 Peter 1:16. But I've noticed there is a famine in the land as far as teaching on holiness is concerned (not to be confused with legalism). And not only is there very few teaching on holiness, but we largely don't have the fear of God anymore either. There is no remorse for personal sins committed, and there is no sense of having to account to God for our behavior and our thoughts which we know are contrary to Scripture. The outcome is believers who may have prayed a sinner's prayer months or years earlier are not confronting wrong behavior (sinful), saying this is wrong and I need to change according to God's word. It's no wonder that much of the western church have now become a user-friendly kind of church. We don't want you feeling bad about things. We don't want to preach a radical message from God's word that will radically change your life.
Over in the gospel of John, chapter six, Jesus said some things that offended the crowds. Many left Him. His disciples said to Him, 'This is a hard teaching; who can bear it?' He looked at them and said, 'Are you guys leaving Me too?' They answered, 'No, we'll stay with you. You've got the bread of life.' But man, this is hard stuff! I don't know about you, but I don't know of any church in this country that is being accused of teaching hard stuff and driving people away, with only a few true disciples remaining to be taught more." Let me close this post out by saying as the seeker friendly church culture explodes, the few pastors and churches that still do put emphasis on genuine godly discipleship, and teach on holiness, the fear of God, and living right according to God's word, will reap the benefits of seeing mature disciples of our Lord Jesus Christ go out and change the culture of compromise within much of the church, and the godless society in which we live in today.
(Any and all comments are encouraged to add to this thread).