Welcome Pierre. I am surprised that the JWs you have encountered, can't explain something as basic as their name as a religion and the rationale for it. They must be a dumber lot than they were in my day. Why shoot, I have be out of the religion for fourty years, and I could still stop at your door and explain it. The name Jehovah is an english version of the pronounciation of God's name, though other pronounciations could be used, such as Yawah. In hebrew, God's name is YHWh, and is referred to as the tetragramiton. It is found throughout the Old Testement. In hebrew writing vowels are not used, so the vowels have to be guessed at, hence there is some ambiguity as to spelling and pronounciation. By their name, JWs are not implying that they have seen God. Their name implys that they should be busy proclaiming God's name so others will become aware of it and of Jehovah's teaching. Regarding the going door to door, they quote a scripture at Acts 20:20.