The most useless thing you can get involved with is a False Teacher.
Read: 2 Peter: 2:17-20
17 These people are as useless as dried-up springs or as mist blown away by the wind. They are doomed to blackest darkness. 18 They brag about themselves with empty, foolish boasting. With an appeal to twisted sexual desires, they lure back into sin those who have barely escaped from a lifestyle of deception. 19 They promise freedom, but they themselves are slaves of sin and corruption. For you are a slave to whatever controls you. 20 And when people escape from the wickedness of the world by knowing our Lord and Savior Jesus Christ and then get tangled up and enslaved by sin again, they are worse off than before.