Are you spiritually dumb? This Christmas, will you talk about your love for Jesus freely and openly? Or are you tongue-tied like Zechariah?
Zechariah's tongue was loosed to praise the Lord when he obeyed the archangel Gabriel by naming his son "John" (Lk 1:63). If you want your tongue loosed, go back to a point in your life where you disobeyed the Lord. You may think that the Lord forgets about His commands after a while, but no, He's still waiting for you.
Two years ago, the Lord may have told you to go to Confession regularly, but you never did it. Obey, and you'll find yourself sharing your faith more freely. Maybe your tongue has only been tied for the two weeks since you have not forgiven a relative of yours. Obey or you'll be silenced for Christmas. You may have never spoken freely of Jesus. So you must go back to the first time you had ever thought of totally giving your life to Him.
Once you obey the first commandment of loving the Lord with all your heart, you will obey the last commandment from Jesus before He ascended. You will be His witnesses (Acts 1:8), proclaim the gospel to all creation (Mk 16:15), and make disciples of all nations (Mt 28:19).
If the devil's got your tongue, it's because you're obeying him. If Jesus has loosed your tongue, it's because you obeyed Him. Obey Jesus and proclaim the Christ of Christmas.