um, a heretic is a person who holds beliefs inconsistent with Christianity.
That would have included several people in the Reformation. I think that we should "judge" a person by his character, not his religion. Actually, I prefer to leave the judging to the Savior himself, for he is the only to who has the true right to do so. There are many good people of all types of religions. I like to focus on that. A Catholic, Mormon, Baptist, or whomever who is sincere in his/her beliefs and strives to do good in this life has my respect.
We are told in Scripture to judge those within the church and ensure that chaff don't get tossed in with the wheat.
But not all faiths offer inherent goodness. I doubt you would find many takers who would advocate that the Pharisees of Christ's day were deserving of 100% "respect." I can hear your mild rebuke of Jesus now..."Come on, JC, you know these Pharisees are sincere in their beliefs...and they strive to do good...woncha knock off these comments about being a 'brood of vipers' and 'whitewashed sepulchres' and being sons of Satan?"
The Bible doesn't advocate according koolaid-drinkers "respect," no matter how sincere their chugging may have been! Nor does it say to leave the judging of religious beliefs up to God alone.
The Bible has many words that describe discernment and wisdom. It also says in 1 Thess 5:21: "Test all things. Hold fast to that which is good."
If you ne'er make judgment calls as to what beliefs are sound, and which ones aren't, then you've just disobeyed this precept.
Hey, we have spiritual filters for a reason. Elsewise, Jesus' and Paul's warnings about spiritual wolves are non-sensical (Mt 10:16; Acts 20:29).