Here is the crux of the gospel.  We learn many more details in reading about  Jesus' words and actions, and in Paul's writings.  these point us to the importance of things like loving our neighbour, obedience to God's will, prayer and lots more.  But here is Paul's statement of the reason behind it all - that Jesus is the Christ , God's Messiah,  that he rose from the dead (and all the implications of that for human-kind) and that he was a descendant of David - and so fulfilled many prophesies of the Old Testament.

V 9.
in whose service I am exposed to hardship, even to the point of being shut up like a common criminal; but the word of God is not shut up.

Serving Christ is no guarantee of an easy ride through life.  Paul's life alone is a testimony to this fact.  But Paul himself shows us that what other people think is important in life was not necessarily important to him, to living as a Christian and serving Christ. Paul suffered a great deal of persecution and hardship and ended his life treated as a criminal.  But so did Jesus!  Paul was following in his Master's footsteps.  Jesus asks us to be willing to do that too - are we willing?

Paul's words are triumphant, even from prison: 'They can shut me up in prison, but they can't shut up God's word!'

Am I prepared to suffer persecution and hardship to serve Jesus?  I have to admit: I don't know!  So far he hasn't asked me to. All I can say is, 'I hope so.' My prayer is that if it becomes necessary for me to suffer persecution and hardship for Christ, that he will give me the strength to do it.

Persecution and hardship. What do they mean for someone who lives a relatively wealthy existence in a society which doesn't really care one way or the other whether I worship God in Jesus Christ or not? (As long as I don't bother anyone else with my beliefs and look as if I might want to put pressure on another person to consider the claims of Christ!  That would not be 'politically correct' ....... would it?)

V 10.
And I endure it all for the sake of God's chosen ones, with this end in view, that they too may attain the glorious and eternal salvation which is in Christ Jesus.
NLT.  I am willing to endure anything if it will bring salvation and eternal glory in Christ Jesus to those God has chosen.

Paul is willing to put up with anything if it means that the good news of salvation through Christ is spread and he can see that there are people being brought into a relationship with God through Christ.

What am I willing to put up with?

I am not sure that most of the Christians I know are willing to be made uncomfortable, let alone suffer persecution, for the sake of spreading the Gospel.  Does this mean that, when it all boils down, we are really just happy that we have been 'saved' and we're  not particularly concerned  about anyone else?

Vs 11- 13
Here are words you may trust:

Paul reminds Timothy (and us) of something Timothy has learned before and should keep in mind.  The New Bible Commentary (p 1307) suggests that these lines may be part of an early Christian hymn that Timothy would have been very familiar with.  The hymns and praise songs we sing in church often remind us of great Biblical truths we need to remember.  We need to sing those songs during the week too.  We have a wonderful resource in recorded music which can help keep those truths in mind. (Paul and Timothy didn't have that luxury!)

The statements remind us of some of the consequences of our faith or lack of it:
If we died with him, we shall live with him.  In Romans 6: 8 Paul wrote something similar: And since we died with Christ, we know we will also share his new life. (NLT)  In that statement, Paul was likening the 'dying with him' to our baptism Romans 8: 4: For we died and were buried with Christ by baptism.  And just as Christ was raised from the dead by the glorious power of the Father, now we also may live new lives.(NLT)   In letting go of our old life and old habits, we gain a better way of living.  That is a promise to remember!  But it takes trust to let go of familiar habits, even those we recognise as bad habits.  We need to remember this as an encouragement when getting rid of old habits seems just too hard; it give s uas a reason to go ahead.

if we endure, we shall reign with him.  Here is a promise that encourages us when life looks bleak and living as a Christian seems just too difficult.  We look around us and see non-Christians seeming to achieve sucess, having fun, doing their own thing and we wonder why we don't have the same luxuries!  We begin to wonder if striving to live as Jesus wants us to is really worth it.  Then we need to remember what we are promised.  We need to remember 'the big picture', not focus on the present moment.  Again, Paul wrote something similar in Romans 8: 17, 18.  And since we are [God's] children, we will share his treasures - for everything God gives to his Son, Christ, is ours, too.  But if we are to share his glory. we must also share his suffering.  Yet what we suffer now is nothing compared to the glory he will give us later. (NLT)

These two statements are positive consequences of keeping faith.  The next one is about the consequence when we don't keep faith
If we deny him, he will deny us. NIV puts it: If we disown him, he will disown us.  This seems a bit harsh and doesn't seem to fit in with the idea of a loving God who loves all his creation - even those who don't love him.  But it makes sense.  God has given us free will - the right to choose what and who we believe in.  If we choose not to throw in our lot with God through Christ, he doesn't force us.  If we are definite about choosing not to be 'owned' by God, he doesn't insist or force his 'ownership' upon us.  That doesn't mean he doesn't love even those who choose to ignore him.  It means that he lovingly allows us the choice. Imagine how much that must hurt him!  It is important that we all understand the implications of the choice we make.  Here Paul has put in in a nutshell!

If we are faithless, he keeps faith, for he cannot deny himself.'   And here's the great news!  God never gives up on the human race.  He'll never stop wanting all of us to turn to him and want to build a relationship with him, even though many of us refuse to do so.  He created human beings because he wanted to be close friends with us and to share with us the good things in his creation.  He has never - and will never - stop wanting that to happen.
In the musical, Children of Eden, 'Father' is made to sing: I have built a universe spectacular and new.  And I sat there in my universe and learned that this was true: What use is a universe with no one to give it to? (Father's Day, Act 1)

V 14.
Go on reminding people of this, and charge them solemnly before God to stop disputing about mere words; it does no good, and is the ruin of those who listen.

So often in our churches we get into discussions - if not arguments - about peripheral things.  We need to stop and think about what is really important and make sure that is the message we are promoting to the world.

New Bible Commentary, p 1307.  That Paul treats this injunction very seriously is seen in the words before God.  The apostle is deeply conscious that quibbles about words are a waste of time and wishes to warn Timothy against this.  It is not always recognised that trivial debates are harmful, but Paul uses a strong word here (ruin), which emphasises the disastrous effect on others.

V 15.
Try hard to show yourself worthy of God's approval as a labourer who need not be ashamed;  be straightforward in your proclamation of the truth.

NLT. Work hard so God can approve you.  Be a good worker, one who does not need to be ashamed and who correctly explains the word of truth.

I remember some years ago turning on the TV and coming across a couple of theologians debating some topic of which I had no understanding and using words that seemed to me to be a mile long.  I did as I imagine most 'normal' people would do: I turned to another channel!  And I wondered what picture of Christians these two - no doubt deeply committed Christian gentlemen - were giving of 'the church'.  If I didn't know better, there is no way I'd go near any church for fear that everyone might be talking like that, and I'd feel such a nincompoop!

Let's be very careful of how we talk about the good news we have to share.

Quest Study Bible. p 1649.  Can we earn God's approval?  No. But we can do our best to allow God's work to show in our lives.  Though we are approved by grace, not works, we demonstrate that we have been approved when the results of his grace in us can be seen.  What we are on the inside is recognised by the evidence we produce on the outside.

New Bible Commentary. p. 1307.  V 15 is a gem of positive advice to the person of God.  The aim is to produce an approved workman (ie approved by God).  This requires effort - yet no-one can do more than his or her best.  There are two requirements - an unashamed approach and a right handling of the word of truth.  The latter will reinforce the former.  Tehe Greek verb translated correctly handles (NIV) really means cutting a straight road and suggests straightforward exegesis (exegesis = explanation or commentary).  This must be the aim of all true teachers of the word.  'Reading into' the text what is clearly not there is of help to nobody but is depressingly common.

V 16 - 18
Avoid empty and worldly chatter; those who indulge in it will stray further and further into godless courses, and the infection of their teaching will spread like a gangrene. (NLT: cancer)  Such are Hymenaeus and Philetus;  they have shot wide of the truth in saying that our resurrection has already taken place, and are upsetting people's faith.
NIV. godless chatter.  NLT. godless, foolish discussion.

Our non-Christian friends can turn on the TV almost any time or read the weekly and monthly gossip magazines for their fill of empty and worldy chatter.  They don't need us for that! This doesn't mean we should be quoting Bible verses in every conversation, either! We can demonstrate, by the way we talk about everyday things, what our values are.

Another source of godless chatter is some of the ideas put forward by people influenced by New Age thinking. This includes some church people.  We hear and read so much that, on the surface, seems to make sense - and fits the ideals of 'political correctness' - that we begin to fit those ideas into our thinking about what we are taught in church or what we read in our Bibles.  We need to constantly go back to the basics of our beliefs and check them out: to go back to what Jesus said and what Paul taught so that our own faith remains strong and we do not influence others away from what the Bible really teaches.

V 19.
But God has laid a foundation, and it stands firm, with this inscription: 'The Lord knows his own', and. 'Everyone who takes the Lord's name upon his lips must forsake wickedness.'
NIV. Neverthelss, God's solid foundation stands firm, sealed with this inscription: "The Lord knows those who are his," and, "Everyone who confesses the name of the Lord must turn away from wickedness."
NLT..  But God's truth stands firm like a foundation stone with this inscription: "The Lord knows those who are his," and "Those who claim they belong to the Lord must turn away from all wickedness."

Whatever we hear spoken and read, God's message remains absolutely true.  When we remember the basics of our faith (as Paul reminded Timothy of them) as we read our Bibles or listen to teaching or discuss spiritual things with others, God's word will stand firm.  God knows who are the people who trust him and faithfully do his work.  We can know who they are by their attitudes and values and the way they live their lives.  And others can look at us and know who we belong to if we live our lives according to the way Jesus taught us.