Heb 5:12-14 For though by this time you ought to be teachers, you have need again for someone to teach you the elementary principles of the oracles of God, and you have come to need milk and not solid food. For everyone who partakes only of milk is not accustomed to the word of righteousness, for he is an infant. But solid food is for the mature, who because of practice(experience)have their senses trained(exercised) to discern good and evil.
Before disciples can move on into maturity, they have to be established in the elementary principles of the oracles of God. Universal reconciliation is mainly the foundation doctrines of the resurrection of the dead(whens) and the doctrine of eternal judgment(whys). Just knowing that all men will be saved, as wonderful as that is, does not make one mature. Understanding repentance from dead works and faith towards God, baptisms, and laying on of hands are also foundational milk that every babe must be nourished by before they can move towards mature discipleship and sonship(Eph. 4:13). Understanding repentance- the state of being that accompanies a broken and a contrite heart, is not about legalism or condemnation. It is about discernment. It is impossible to prove what is the good, complete, and acceptable will of God unless someone understands why repentance is fundamentally necessary to receiving the reconciliation, and continuing in it, because "we all fall short in many ways".
Heb 6:1-9 Therefore leaving the elementary teaching about the Christ, let us press on to maturity, not laying again a foundation of repentance from dead works and of faith toward God, of instruction about washings and laying on of hands, and the resurrection of the dead and eternal judgment. And this we will do, if God permits. For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit, and have tasted the good word of God and the powers of the age to come, and then have fallen away, it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame. For ground that drinks the rain which often falls on it and brings forth vegetation useful to those for whose sake it is also tilled, receives a blessing from God; but if it yields thorns and thistles, it is worthless and close to being cursed, and it ends up being burned.(1 Cor 3:13-15, John 15:6) But, beloved, we are convinced of better things concerning you, and things that accompany salvation, though we are speaking in this way.
You cannot leave the foundation until it is laid. God will not permit it. It has be to labored over until the disciple understands. Very few "Christians" have tasted the powers of the age to come because they are babes and the Father will only give them "popguns," not pistols. No real power can abide upon those who refuse the cross and the sword. Those who understand the preaching of repentance know that Jesus, Peter, Paul and John all understood the reconciliation of all, but nevertheless declared openly the works of disobedience, the spirits in rebellion, the fruits of their works, and their past, present and impending disciplines. They were not speaking in some elaborate allegorical code, either. Fully knowing that God's kind intention which He purposed in Himself is the summing up of all things under one Head, even Jesus- through reconciliation- they nevertheless continually exhorted the saints to good works and reproved the works (and workers) of unrighteousness. Again, this is not about damnation or condemnation- it is about discernment- knowing and declaring what God approves and disapproves. This in context with the overwhelming first place of the message of God's love, but it is also the message of loving God. It is a part of the maturity cycle, along with meekness, humility, forgiveness and above all, love. If the love of God suffers insult from discernment and reproof then all of the apostles and prophets and the Lord Jesus Himself owe it an apology. It is time to put away childish things, and become mature in our understanding(1 Cor 14:20).
Eph 4:11-24 And He gave some as apostles, and some as prophets, and some as evangelists, and some as pastors and teachers, for the equipping of the saints for the work of service, to the building up of the body of Christ; until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a mature man, to the measure of the stature which belongs to the fullness of Christ. As a result, we are no longer to be children, tossed here and there by waves and carried about by every wind of doctrine, by the trickery of men, by craftiness in deceitful scheming; but speaking the truth in love, we are to grow up in all (pas)aspects into Him who is the head, even Christ, from whom the whole body, being fitted and held together by what every joint supplies, according to the proper working of each individual part, causes the growth of the body for the building up of itself in love. So this I say, and affirm together with the Lord, that you walk no longer just as the Gentiles also walk, in the futility of their mind, being darkened in their understanding, excluded from the life of God because of the ignorance that is in them, because of the hardness of their heart; and they, having become callous, have given themselves over to sensuality for the practice of every kind of impurity with greediness. But you did not learn Christ in this way, if indeed you have heard Him and have been taught in Him, just as truth is in Jesus, that, in reference to your former manner of life, you lay aside the old self, which is being corrupted in accordance with the lusts of deceit, and that you be renewed in the spirit of your mind, and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth.
Repentance, righteousness and holiness are not about legalism or works based salvation, they are about transformation, the renewed mind and receiving the heart of the one who laid down His life for His friends, including us in particular in this evil age. It is a friendship many reject and will not know until the ages to come, which causes us pain and labor. We are to love everyone, and lay down our lives for the reconciliation of all. This ministry includes the persecution and the rejection that comes from preaching righteousness in the midst of a perverse generation.