News Flash: We are to trust the Lord in all things, and follow His leading!Yet, if a safe haven were to be available to Christians during the tribulation, such would get mentioned in the word.
As it is not and as we do not know which parts of the globe will lose drinkable water, grazing etc. we would not know where to build such a place.
This is very much like the doomsday prophets making predictions of His return when no one knows.
When do you expect it?
BTW, as you do not believe in eternal security, how do you know the people that join your safe haven will not betray you as they fall away.
Ref. e.g. John 10:27-28, John17:3