These things command and teach.  Let no man despise thy youth; but be thou an example of the believers, in word, in conversation, in charity, in spirit, in faith, in purity.  Till I come, give attendance to reading, to exhortation, to doctrine.  Neglect not the gift that is in thee, which was given thee by prophecy, with the laying on of the hands of the presbytery. Meditate upon these things; give thyself wholly to them; that thy profiting may appear to all.  Take heed unto thyself, and unto the doctrine; continue in them: for in doing this thou shalt both save thyself, and them that hear thee.
1 Timothy 4:11-16

It will be better explained as to what the apostle Paul is writing to Timothy about if you will read the whole chapter.  However, verses six through ten will help.

Timothy was a young pastor which Paul had trained, and taught many good and godly things.  Some of it is good reminders of how all Christians ought to live; but especially those who preach the word of God, and lead us in spiritual matters related to the cross of Jesus Christ.

Notice what Paul encourages Timothy to do:  Give attention to reading, probably of the Scriptures in the Church services, but also for one’s own personal growth and benefit; then attention to exhortation, or the explaining the text, then teaching  how that text applies to us; then to doctrine which is teaching or giving instruction of what to do and how to do it.  The Old Testament was all they had.  Some or all of the Gospel accounts may have been in scroll form by the time of Paul.  Paul did write many of the epistles (letters) to the churches he started, and personal ones like the Timothy, Titus, and Philemon Epistles.

The doctrine most precious to continue teaching is that all of Adam kind (mankind) has sinned, and separated from God.  That God in His loving kindness had and has the only way to have fellowship with Him.  That is through the shedding of innocent blood.  The blood of lambs, and bulls and goats was insufficient, requiring daily and annual sacrifice.  All these were pictures/types pointing to the coming of Messiah who would be the perfect blood sacrifice for  our sin.  Jesus Christ fulfills all the prophecies concerning the Lamb of God who came to take away our sin.  Jesus died on the cross for our sin, He was buried, and He rose again the third day proving every word He had spoken concerning Himself.

That is the hill I choose to stand on and fight for.  The cross of Jesus Christ and His coming again.