Joel. R. Beeke:

Covenant theology does not negate the need for us to evangelize our children, nor does it discourage us from doing so. Scripture offers no guarantees for the salvation of our children, but the covenant of grace offers us a great deal of hope outside of ourselves in a sovereign, covenant-keeping God, who will not forsake the works of His own hands (Ps. 138:8). Covenant theology should encourage us to evangelize our children as we daily, prayerfully, and expectantly depend upon the triune God for His blessing upon our efforts. (p. 10)

He writes in his book, Bringing the Gospel to Covenant Children 10 specific doctrines to emphasize in evangelizing children:

1. Teach them who God is and what He is like
2. Teach them the seriousness of sin.
3. Teach them what the Bible says about unrepentant sin.
4. Teach them that they must be born again (Ps. 51:6,7,10; John 3:3-5).
5. Teach them about the moral law and its uses (i.e., civil, evangelical and didactic).
6. Teach them that the atoning blood of Jesus Christ is the only way of salvation.
7. Teach them the necessity of faith in Jesus Christ.
8. Teach them about Jesus Christ.
9. Teach them about sanctification and holiness.
10. Teach them about the joy of heaven

Download Bringing the Gospel to Covenant Children by Joel R. Beeke.