"From each according to his abilities, to each according to his needs." -- Karl Marx.
"From each according to their ability, to each according to their needs." -- Constitution of the Union of Soviet Socialist Republics, 1936, Article 12.
One of the cruel premises of communism, as it came to be in practice (with Lenin and Stalin and Mao), was that the collective material benefit (food, shelter, clothing) always outweighed the individual material benefit - and even worse, outweighed the value of individual life. If by 'altruism' you mean the overall collective material benefit, well, communism could be called 'altruistic.' So, you have your definition for that word. But so what? Lenin, Stalin and Mao had a morality which condoned the slaughter of millions. Christian morality is supremely different. Christian morality seeks that each improve himself by more closely following the example of the sinless Christ. As such, that the collective (society) benefits follows from this personal conversion. In short, Leninist morality sought to materially improve society with no regard for human life. Christianity seeks to improve individuals, confident that society will improve as well.