How and why Christ was able to ascend
From the Gospel of Truth:
For now, their works lie scattered. In time, Unity will complete the realms. Within Unity each one will receive themselves, and within knowledge they’ll purify themselves from multiplicity into Unity, consuming matter within themselves like fire, and darkness by light, death by life. If indeed these things have happened to each one of us, then it’s right for us to think about all, so that this house will be holy and silent for the Unity.
If you look at his qualities:
- he could not lie
- he could not act from ill intent
- he is a righteous judge (it's a balancing act)
You can see that these are the qualities required for ascension. There's one more thing though: it is the burden of the heart commonly known as guilt. Due to these qualities and because his heart was light like a feather he was able to ascend. He didn't carry any kind of heavy guilt in his heart that would hold him down from ascension. And he effortlessly forgave any/all transgressions against him.
So how could others ascend? It is to reach the same qualities and same lightness of heart by redeeming oneself. One unburdens one's own heart of guilt by confessing the Truth and making past wrongdoings right. If e.g. you've stolen someone's money, you can redeem this by confessing and returning what was stolen. If after receiving the confession of Truth they are not able to forgive it remains their burden and not yours. They will carry the burden of unforgiveness in their heart which will only prevent their own ascension.
So the key is: unburden your heart by confessing the Truth of all guilt and making it right. Naturally these works of redemption would cause much 'tribulation'. Upon completion of Unity no works lie scattered as they have all been made right. This means each and everyone has finally completed their own works.