The heathen entered into her sanctuary...

The local "church" or "assembly" ought to be one focused on edifying and equipping the saints to live for God and to seek and save the lost.

They ought not to fall into the same error that the people did in Jeremiah's time.

Jeremiah said:  "The adversary hath spread out his hand upon all her pleasant things: for she hath seen that the heathen entered into her sanctuary, whom thou didst command that they should not enter into thy congregation." Lamentations 1:10.

Sad but the modern churches for the most part have fallen into this error.

We have plenty of New Testament scriptures that direct us as well such as:

Prove all things; hold fast that which is good. Abstain from all appearance of evil. ! Thessalonians 5:21-22

And have no fellowship with the unfruitful works of darkness, but rather reprove them. Ephesians 5:11

Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? And what concord hath Christ with Belial? or what part hath he that believeth with an infidel? And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people. Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you...2 Corinthians 6:14-17

And some people wonder why so-called Christian church's are becoming more and more like the world and drifting further and further away from God...Jeremiah called it out and we should know better.