What to teach young men

Ephesians 5:25

Husbands, love your wives, as Christ loved the church and gave himself up for her,

2 Timothy 1:6

For this reason I remind you to fan into flame the gift of God, which is in you through the laying on of my hands,

What to teach young women

1 Timothy 5:11

But refuse to enroll younger widows, for when their passions draw them away from Christ, they desire to marry

Ephesians 5:22

Wives, submit to your own husbands, as to the Lord.

The condition of continued life in Christ

Hebrews 3:6

but Christ is faithful over God's house as a son. And we are his house, if indeed we hold fast our confidence and our boasting in our hope.

Hebrews 3:12-14

Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God.  But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin.  For we have come to share in Christ, if indeed we hold our original confidence firm to the end

Hebrews 4:11

Let us therefore strive to enter that rest, so that no one may fall by the same sort of disobedience.
Hebrews 6:4-6

For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit,  and have tasted the goodness of the word of God and the powers of the age to come,  and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt.