# I know and am persuaded in the Lord Jesus

"I am certain because of my relationship with the Lord Jesus"

# nothing is unclean by itself

"everything by itself is clean" 

# by itself

"by its nature" or "because of what it is"

# Only for him who considers anything to be unclean, for him it is unclean

"But if a person thinks something is unclean, then for that person it is unclean and he should stay away from it"