No, God cannot allow sin to enter heaven
How do you explain Satan being up in heaven?
7 The LORD said to Satan, "Where have you come from?" Satan answered the LORD , "From roaming through the earth and going back and forth in it." Job 1:7
Or Revelations 12:7-9?
7And there was war in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. 8But he was not strong enough, and they lost their place in heaven. 9The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.
This in the "end times" and I don't believe this has happened yet.
Then I heard the voice of the Lord saying, "Whom shall I send? And who will go for us?" And I said, "Here am I. Send me!" Isaiah 6:8
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