1. You cannot speak for what the "christian" believes. You can only speak for the individual Christians who have actually told you that this life is of no importance when compared to the next (which if I were a wagering man, I would wager have not been many at all).
2. In the event you did happen to have a christian tell you what you claim they have, then they are wrong. The scriptures actually paint a very different picture.
3. You cannot speak for your fellow atheists. You can speak, at most, for those who have intimated to you that they share your particular views. Not all atheists hold the view that you do regarding the importance of this life.
4. I am a Christian and my beliefs do not make life meaningless.
Correct these misconceptions you have because if you do not, then you are no different than the Christian who makes generic, blanket statements about atheists.