I'm not. Like I said, I don't believe in aliens. But if you believe in aliens, and you believe they are "sinless" then the are on par with God, LIKE God, being sinless, perfect. This is a fact. This would mean that they are "little Gods". So basically, to believe they are sinless means that by default one is polytheistic.
Totally wrong since you are equating sinlessness = God.. There are many other qualities that constitutes God, omni-present, omni-scient and all powerful.
God can may well have created beings that are 100% obedient and thus by definition are sinless.
Who are you to claim otherwise? As I said absence of evidence is not evidence of absence.
New International Version (©1984)The secret things belong to the LORD our God, but the things revealed belong to us and to our children forever, that we may follow all the words of this law.
New Living Translation (©2007)"The LORD our God has secrets known to no one. We are not accountable for them, but we and our children are accountable forever for all that he has revealed to us, so that we may obey all the terms of these instructions.
English Standard Version (©2001)“The secret things belong to the LORD our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law.
This IS in the Bible and it makes clear that there are things that we do not know and that are not shown to us by God.. Hence claiming 'if its not in the Bible its not true' is absolutely false since not everything is in the Bible to begin with, only those things God has deemed that we need to know. Therefore, (as I said before), we cannot say eitherway it is unknowable, (unless we had a direct visitation

)
Therefore if there was a need for redemption for these other beings it certainly wouldn't be claimed in the Bible, (as I said), the Bible is focused on Earth... Aliens from another world are not from Earth hence are not relevent to the Bible and thus are grounds for why its not included.