Summary: Paul's closing words summarise what has been presented to Timothy in this letter.
“O Timothy, guard the deposit entrusted to you. Avoid the irreverent babble and contradictions of what is falsely called ‘knowledge,’ for by professing it some have swerved from the faith.
“Grace be with you.” 
It is no secret that I am a news junkie; I fill my spare time with news reports, even watching news reports while eating my lunch. Unquestionably, my favourite news programmes are on Fox News Channel. My addiction leads me to set aside time for an afternoon coffee while watching Bret Baier’s Special Report. When turning on the television during a break in the afternoon to permit watching Special Report on Fox News, I frequently catch the final few moments of “The Five,” the show that precedes Special Report. That show almost always closes with a segment called “One More Thing.”
The “One More Thing” segment consists of brief items that have drawn the interest of the panel members. The items may be something of personal interest, a humorous news item or some serious point that needs to be stressed. As I read the text for this particular message, my mind was drawn to that segment of “The Five.” The Apostle is saying to the young pastor, “O, yes, one more thing.” This one more thing is a summary of all that Paul has written to Timothy.
It would be easy to dismiss these final statements; but dismissal would be a mistake. Christians will benefit from refreshing their memories by focusing, even for a brief while, on Paul’s final reminder. We will benefit because has seen fit to include this warning in the Word. Obviously, He considered the danger to be real and the warning vital. We will benefit from focusing on what the Apostle has written because we who would follow the Master still face this particular danger and similar dangers. Moreover, we will benefit because through study of what the Spirit has included will equip us to think logically and critically. With that, let’s get into the text to see what the Spirit is saying to the churches.
ONE MORE THING — “O Timothy, guard the deposit entrusted to you.” The urgency driving Paul as he writes is conveyed by the construction of the sentence. The Apostle uses the vocative, “O Timothy,” addressing Timothy directly, pointedly demanding his full attention. What Paul is about to say serves as a summation of the entire letter in a single sentence. It is as though the Apostle has added this postscript saying, “Timothy, this is really, really important.” It is Paul’s way of saying, “Oh, yeah, one more thing!” This final charge expresses in succinct form the purpose and the theme of the letter; for one last time it expresses the Apostle’s concern.
Having grabbed the elder’s attention, Paul rushes to ensure that Timothy understands that the elder is responsible to be on guard. Modern church-goers are often uncomfortable if the elder appears to be aggressive, at least in their estimate. Admittedly, there is no warrant for meanness; nor may an elder be pugnacious or combative either physically or verbally. However, the elder is to be a warrior. He is charged with the responsibility of guarding God’s flock and of keeping the commandments of God. He is defender of the Faith, resisting the insinuation of error and snatching the unwary from danger that is always lurking nearby.
Speaking of guarding the deposit, Paul employed a word [phylássō] that speaks of guarding closely, of watching or of obeying ; it carries the connotation of defending a person or a position.  Thus, the word is quite descriptive, speaking of the responsibility imposed on Timothy as the elder of the congregation. As God’s undershepherd, he is a defender of the flock.
Earlier, Paul used this word in a charge given Timothy. “In the presence of God and of Christ Jesus and of the elect angels I charge you to keep these rules without prejudging, doing nothing from partiality” [1 TIMOTHY 5:21]. In his next letter to Timothy, the Apostle would use this same word to caution against Alexander the Coppersmith. “Alexander the coppersmith did me great harm; the Lord will repay him according to his deeds. Beware of him yourself, for he strongly opposed our message” [2 TIMOTHY 4:14, 15]. It begins to give an idea of Paul’s concern.
Let’s look at some other instances of where this particular word has been used in Scripture. In His High Priestly prayer, the Master stated to the Father, “While I was with [the disciples], I kept them in your name, which you have given me. I have guarded them, and not one of them has been lost except the son of destruction, that the Scripture might be fulfilled” [JOHN 17:12].
When Paul had presented his case before Felix, the Roman governor deferred making a judgement. “He said, ‘I will give you a hearing when your accusers arrive.’ And he commanded him to be guarded in Herod’s praetorium’” [ACTS 23:35].