What does not contribute to the effectiveness of the delivery of a speech?

religion
tone
clarity
organization

Religion, because tone, clarity, and organisation can influence the effectiveness of the delivery of a speech. 
If one uses a sad or solemn tone during a speech of happiness, the effectiveness will decrease. If there is no clarity or organisation, the topic may be lost. Religion does not contribute to the effectiveness of the delivery of a speech, because different ethnic backgrounds should not affect performance. 

The one that does not contribute to the effectiveness of the delivery of a speech is :
Religion
Religion is simply a personal belief and has nothing to do with speech delivery

Hope this helps