If a muslim is comparing the beliefs of the two religions it must mean that he has already heard the Good News (i.e. been evangelized). At that point we should gently correct any misconceptions they might have about Christianity and be supportive of any seeds the Holy Spirit may have planted.
I try, I really do, to act Christlike in my dealings with non-Christians. Unfortunately, I have a harder time with some than with others. I have a number of other short-comings that I know God disapproves of, and that I have to work on with the help of the Holy Spirit.
That whole revenge thing, for example. Vengeance may be the Lord's, but sometimes I want to help Him out a little.
I could use a few prayers on this. Not that I actually take any other than minor, petty revenges, but that I feel so badly about it when I don't.
OK, that was a little off subject, but I'll let it stay.
Or it means that he fully supports Islam over Christianity and is pointing out that Islam states that Jesus will destroy Christianity.
The religions are polar opposites and Islam is the enemy of the free world.