Be Children in Mischief, Adults in Righteousness

Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature. (1 Corinthians 14:20)

Childlishly enthused with his new toy,
Opie killed the mama bird, leaving 3 orphans

Here, Paul is admonishing the Corinthians for over-valuing tongues (glossolalia). The church was entranced by the 'show' of tongues and interpretation of tongues.They had become unduly entranced by this next 'shiny new thing' (kind of like a mega-pastor with a fog machine or a boy with a new slingshot).
Pulpit Commentary says-

The Christian should always be childlike (Matthew 11:25; Matthew 19:4), but never childish (1 Corinthians 13:11; Ephesians 4:14).

Good advice. To often in this day and age, pastors leave one fad to leap on the next so as to appear relevant. Surfing from Jabez Rugs to Daniel Fasts, Courageous Resolutions to Love Dares, Promise Keepers to Beth Moore bracelets, Be Still to Labyrinths, Seeker Sensitive to Emergent, tongues to healings, it often leaves out the most important: JESUS. Pastor Phil Johnson speaks harshly about the Flaws of a Fad Driven Church. A Charismatic fascination with tongues had swerved the Corinthian Church from its underpinnings and caused all sorts of divisive issues.
Going further, Gill's Exposition says,

The apostle here has chiefly reference to the gift of speaking with tongues, these Corinthians were so desirous of; which when they had it, was only to talk like children; and for them to prefer it to other gifts, which were more useful and beneficial, discovered their judgment to be but the judgment of children; and if they desired this, and made use of it for ostentation, it showed a childish vanity, from which the apostle here dissuades.

Matthew Henry says -

Children are apt to be struck with novelty and strange appearances. They are taken with an outward show, without enquiring into the true nature and worth of things. Do not you act like them, and prefer noise and show to worth and substance; show a greater ripeness of judgment, and act a more manly part; be like children in nothing but an innocent and inoffensive disposition. A double rebuke is couched in this passage, both of their pride upon account of their gifts, and their arrogance and haughtiness towards each other, and the contests and quarrels proceeding from them.

Note, Christians should be harmless and inoffensive as children, void of all guile and malice; but should have wisdom and knowledge that are ripe and mature. They should not be unskilful in the word of righteousness (Heb. 5:13), though they should be unskilful in all the arts of mischief.

In today's cluttered world, there are many things that compete for attention. In the Church it is the same. Fads, things that seem good or even biblical, are simply stumbling blocks. It's hard to understand how a Spiritual Gift could be one of those stumbling blocks, but this simply proves that satan can make hay out of anything. He made a piece of fruit Eve saw every day look so good that Eve was drooling over it and with her husband caused the downfall of man! Disobedience can come anywhere at anytime.
The childish mischief is complicated but the solution is simple. Jesus. Stay in your word, stay praying, stay streamlined in your quiet time. Strip away the clutter, lay aside every weight, focus on the Holy One.