(On the question "How we know that only the Bible is the written and actual word of God, when other religion's book claim the same?")

The argument is not “The Bible is the Word of God because it says it is.” Rather, the argument is “The Bible is the Word of God because it says it is and any alternative leads to absurdity.”

If the Bible were not the Word of God, we would have no foundation for all the things we take for granted, such as laws of logic, uniformity of nature, and morality. The law of non-contradiction, for example, is based on the self-consistent nature of the biblical God (2 Timothy 2:13). The Bible itself tells us that all knowledge depends upon God (Proverbs 1:7; Colossians 2:3). Most other religious books do not make the claim that all knowledge is deposited in their god; and if they did, they would not be able to make good on the claim. Therefore, the argument will only work for the Bible.