First of all, rvikz dude, there is no such thing as “Mohammedans” or “Mohammedanism”. While followers of Jesus Christ call themselves as Christians, the followers of Prophet Muhammad (Sallalah o Alaihay Wassalam) are called Muslims and the religion is called Islam. Get this straight.
Second on the issue of “Kafir”, this has been debated and clarified a number of times, just to reiterate, here is an old post. Some relevant cut and pastes are as follows (it was originally posted by Mr PartyPooper):
“Every Kafir is a non-Muslim, but not every non-Muslim is a Kafir.”
The above statement quite neatly captures my view on this subject. This remaining post elucidates upon why I believe this is so…
OK… here we go… another cut&paste job!
From Understanding Islam
“Kaafir” in the Arabic language means “rejecter”. The term “Kaafir”, normally taken to be synonymous with “non-Muslim” or “non-believer” is quite different from the two terms. A “non-Muslim”, obviously, is a person who does not adhere to the Muslim faith. Thus, all those who do not ascribe to the Muslim faith are “non-Muslims”. A “non-believer”, generally used for a person who does not believe in God and the Day of Judgment. “Kaafir”, on the other hand, is a person who knowingly rejects the truth. A person may not believe in some ‘truth’ for a number of reasons. For instance, he may not be fully convinced of some aspect of that ‘truth’ or he may have some doubts in his mind regarding that truth. However, if all doubts are removed from his mind and he becomes fully convinced of that truth, yet he persists in not accepting it or persists in ascribing to a wrong belief after becoming certain of its incorrectness, he then becomes a “Kaafir” and is no longer just a “non-Muslim” or a “non-believer”.
In other words, all those people who persist in not accepting Islam after being fully convinced that Islam is the true religion of the Almighty or persist in ascribing to a false belief after being convinced of its incorrectness are “Kaafirs” or rejecters of the truth. All others for our purposes are “non-Muslims” or “non-believers”.
This explanation, if considered closely, should clarify the fact that we cannot call anyone a “Kaafir” unless we have absolute knowledge of the reasons for his rejection of faith (or Islam), which we do not possess. Thus, for the purpose of this world, we should not call anyone a “Kaafir”. It is only God, Who with His absolute knowledge can declare someone a “Kaafir”. No one besides God possesses the knowledge that is essential to declare someone a “Kaafir”.