Muhammad is not the father of any of your men, but (he is) the Messenger of Allah, and the Seal of the Prophets: and Allah has full knowledge of all things.
— The Qur'an – Chapter 33 Verse 40
Thats irrelevant brother. Also a completely different subject altogether.
Your question was about "the redeemer" and "the christ". The redeemer is the Mahdi, not Muhammed.
Through Moses, Christ and Muhammad there is redemption for the people who are sincere and follow their Teachings. That is clear as the noon day sun. To imagine it would be different with the Mahdi or Return of Christ makes no sense to me. You go your way and I’ll go mine.
If it doesn't make sense to you brother, what's your explanation?
The Prophet is more worthy of the believers than other men.(Quran 33:6). We see also many of those whom Muhammad had exhorted to turn towards Allah, were faithless when truly tested. When the battle came they fled. Before becoming Muslims they had been pagans and we know what the Quran says about the polytheists and unbelievers. So when Muhammad refers to Prophets He refers to Himself but also the Prophets that have gone before with special emphasis on Moses and Jesus. However there are many other Prophets too beginning with Adam, including Joseph and David and ending with Himself.
So if a seal is where it ends Muhammad is where the Prophetic cycle both begins and ends for that period of time. There is no mention of eternity. The Prophetic era has been sealed by Muhammad until the Madhi and Christ returns to unseal it and redeem the people.
That is how understand it. Your beliefs are yours as mine are mine.