Here are some good posts on doctrine:

Doctrine Matters: Eternal Life Depends Upon It – Kevin DeYoung
Christianity is much more than getting your doctrine right.  But it is not less.

Take a Quiz on Christ – Tim Challies
How well do you know what the Bible teaches us about Jesus?

Your Highest Privilege – Tim Challies
Of all the privileges that are ours through the gospel, which is the greatest? According to many theologians, there is no privilege higher than adoption.