"We can sin now, and we can sin in heaven"
What Bible do you guys use? Have you never read Revelation chapter 21?
""And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away." (verse 4)
And, in verse 8 we are told:
""But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death."
When we get to heaven, which is "free from sin", and the deceiver, the devil will not be there, and our sinful human natures will be changed to be like that of our Blessed Saviour. How, then can you say that we "will be able to sin". Who is going to tempt us? God? If the person who is the cause of our sinning, the devil will not be in heaven, then it can only be that "we will NOT be able to sin".
Before the fall the devil was roaming about, and was able to temp Adam and Eve to disobey God. But, Scripture informs us that the devil will be cast into the lake of fire.
Heaven is without sin.