Even the way you have made that statement is false. It is God Himself who IMPUTES righteousness to the sinner who repents and believes on the Lord Jesus Christ. So no one imputes God's righteousness to himself, unless he is plain stupid.Another example is the false doctrine of imputing righteousness (God's even) on oneself...
The Jewish religious leaders were trying to establish their own righteousness, which is another matter, and which was delusional. And Paul addresses this also.
But how can the doctrine of imputed righteousness be false when it is solidly embedded in Scripture? Which means that you -- an alleged teacher -- are clueless about a fundamental Gospel truth. If you do not know the meaning of justification by grace through faith (which includes the doctrine of imputed righteousness) you need to go back to square one and study the book of Romans for starters. However, what you should not be doing is ATTACKING Gospel truth. That is the work of the devil.