Are Christians born again as mature spiritual people?
No. The spiritual life parallels the physical; no one is born into God's family as a full, mature spiritual person. Every believer enters salvation as a babe in Christ, so failures and growth are expected, just as an infant must mature.
Les explains that the spiritual life is a parallel with the physical. He teaches that you do not get born into the family of God a full, mature spiritual person; instead, everyone comes into a salvation experience as babes in Christ. Because of that, there will be failures. He compares it to an infant who is not trained, and illustrates with an old evangelist who could identify homes with babies by the diapers hanging on the clothesline. Infant believers must likewise grow from that beginning.