## They will  ##

"These people will"

## forbid to marry  ##

"forbid believers to marry" or "prevent believers from marrying"

## forbid ... to receive foods ##

"require people ... to abstain from foods" or "stop people ... from eating foods" or "not allow people ... to eat certain foods." The "people" here are probably "believers" (UDB).

## believers who came to know the truth  ##

"believers who know the truth" or "believers who have learned the truth"

## nothing that we take with thanksgiving is rejected ##

"we do not throw away anything we thank God for" or "we do not disapprove of anything we thank God for" or “everything that we eat with thanksgiving is acceptable”

## it is consecrated through the word of God and prayer ##

"we have set it apart for God's use by obeying God's Word and praying to him" or "we have set it apart for God's use by a prayer that agrees with the truth God has revealed" (See: [[rc://en/ta/man/translate/figs-hendiadys]])