Being blown about with every wind of doctrine (Eph 4:14) is the fate of baby Christians who do not develop a sure foundation in Christ through sound teaching and study of the Word of God with the help of the Holy Ghost. A mature believer is exercised in understanding right and wrong (Heb 5:13-14). The apostles were examples of strong and mature men of God. In their writings, which are inspired by God, we see evidence of their keen discernment and condemnation of wicked heresies and behavior with many warnings of false prophets/deceivers that will come into the church to "make merchandise" of it. They also and necessarily teach the way of the Lord in truth very clearly, enumerating the doctrine of Christ, expanding upon it to clarify it to all who listen. And they back up the teaching with their lives, even to death.
Yet how few really heed the warnings? Naivety is part of being a young Christian, even as it is part of being a child. It is good in regards to learning the evil ways of this world, but dangerous in regards to being led astray into error.
We do not put children on the battlefront of war with weapons in their hands to fight deadly enemies, do we? Neither does God do this in his kingdom. God grooms men and women to know Him and His Son and the Holy Ghost, so that they will discern what is not of God or Christ or the Spirit. This training requires time. But not all who have lived many years as a Christians are necessarily mature. Unlike the physical body which matures simply with age and basic diet, the spiritual man is not so. They must be exercised in another way to grow. Sound teaching and obedience to Christ are vital, but if these are lacking, a Christian can stay a baby for many years.