Maturity requires growing up healthily, relating appropriately and learning practically. The same is true for every believer in Jesus. Although a child could indefinitely redo the first year of nursery/kindergarten/pre-school it would not lead to maturity. The lessons learned need to be worked through practically to form a foundation upon which a lifestyle is built. Relaying the foundation, over and over again, will not enable walls to be constructed or the house built. So it is, growing up into Christ.