Who is the liar but the one who denies that Jesus is the Christ?  This is the antichrist, the one who denies the Father and the Son.  No one who denies the Son has the Father; everyone who confesses the Son has the Father also.  Let what you heard from the beginning abide in you.  If what you heard from the beginning abides in you, then you will abide in the Son and in the Father.  And this is what he has promised us, eternal life.  I write these things to you concerning those who would deceive you.  As for you, the anointing that you received from him abides in you, and so you do not need anyone to teach you.  But as his anointing teaches you about all things, and is true and is not a lie, and just as it has taught you, abide in him.  And now, little children, abide in him, so that when he is revealed we may have confidence and not be put to shame before him at his coming.

There is more than one way to deny Jesus.  We can deny him through neglect of the message we have received.  The truth that Jesus is the Christ is not an abstract truth.  It is not one truth among many so that we should remain indifferent or unaffected.  It is not a truth that wearies, grows dim, uninteresting or old.  It is a truth the nature of which must be kept carefully guarded by the human heart from all those interior and exterior influences which would in any way steal it, diminish it, not care for it, disrespect it or abuse it.  It is a flame, the flame of our soul given us by God himself and which we must guard and protect from the elements as though our very lives depended on it.  For indeed  our eternal life does depend on it.  Let what you have heard remain in you.  And what you have heard is that a Savior is born to us, Jesus Christ the Messiah and Lord.  May we have the heart of Mary who, when she heard these things "treasured them and reflected on them in her heart." (Luke 2.19)

A prayer-

Lord Jesus please help me keep what I have heard carefully in my heart, pondering on it throughout this day so that I may have life.  Amen.