I have always believed that you shouldn't argue about religious matters


  But what really opened my eyes was Romans 1:28.  And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ougth not to be done.  They were filled with all manner of unrighteousness, evil, covetousness, malice.   They are full of envy, murder, strife, deceit, maliciousness.  They are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, etc. 
Then verse 32  Though they know God's decree that those who practice such things deserve to die, they not only do them but give approval to those who practice them.

As I understand it - we do not argue with these people, we do not join them either, we witness God's love and ways and let God handle the outcome.  Which Paul talks about in 2 Timothy says
2Tim 2: 23- 25 Have nothing to do with foolish, ignorant controversies; you know that they breed quarrels.  And the Lord's servant must not be quarrelsome but kind to everyone able to teach patiently enduring evil, correcting his opponents with gentleness.