Why would someone join a group/organization which holds beliefs and practices they disagree with? Either they think the group/organization is insincere about those beliefs and practices or they want to destroy the group/organization from within.
Those who embrace unholiness in the name of love undermine the sovereignty of God. It is like inviting termites into a house. Over time everything that supports the house will be come weak and crumble until the house ultimately falls.
Believers are to reflect God’s holiness in this wicked world. God will save and sanctify those who respond in faith to His Gospel message.
Having a form of godliness but denying the authority thereof is like building a house over a terminate mound. The same is true about celebrating sinful behavior and teaching false doctrine in a church. Eventually people will fall spiritually but God is able to repair their lives and those churches that have fallen prey to these spiritual termites. Repent of the sin and return to Him.
He is a rewarder of those that diligently seek him.