Jesus teach importance of forgivenes but also realise there exist bad people. Luke 22:36 "Then said he unto them, But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one."

On tax, Jesus was giving that response to an entraping question from Pharisees they asked because He had in past criticised of harsh tax policy. Force tithing is not a thing of New Testament but old.