DENVER—A man was sentenced to nearly 20 years in prison on Friday for plotting to bomb a historic Colorado synagogue last year by a judge who described the case as “dripping with Nazism and supremacy.” Judge Raymond P. Moore set the 235-month sentence for Richard Holzer, 28, and imposed a 15-year term of supervised release. Throughout the sentencing trial, Moore expressed harsh criticism of Holzer’s previous statements to undercover FBI agents and social media accounts—describing Holzer’s life as filled with violent and hateful imagery. “It is one of the most vulgar, aggressive, evil crimes that can be committed against an entire group of persons,” Moore said. Holzer’s defense team argued that his suffering of fetal alcohol syndrome influenced his development into adulthood and contributed to his “unmet and overwhelming need to seem more important than he is.” The defense asked the judge for a shorter sentence for Holzer to benefit …