To a lot of Christians, it would seem to be safe to go to a "Christian" church, a "Christian" concert, or any other "Christian" event. After all, it's "Christian". I use quotations because for the last decade or so, churches and other events seem to just throw the term Christian onto whatever it is they're promoting. Unfortunately, a lot of true believers will run to these events or churches that are labeled Christian. Unfortunately, churches also type up anything they want and it can sound really good and Biblical, but one has to go to this church, and maybe for a while, before the truth is revealed, even though it seemed really good online.
With one time or annual events, it might be pretty easy to distinguish pretty quickly certain errors. There are a few passages in the Bible that commands the believer to test and prove these things against scripture. Anything that a believer involves themselves in needs to be examined through the lens of scripture. That's not easy to do, especially when so much of what goes on is labeled as Christian.
There's a number of verses that warn the believer of dangers throughout the world, and there are also some very clear verses commanding that the believer think, pray and research before jumping into that "christian" get together or attending that "christian" church. One word that is common in the following verses is to approve, prove, or try. Ok, 3 words, but looking at the Greek, they all mean the same; to examine, prove, or deem worthy.
1 Thessalonians 5:21
1 John 4:1
If the Bible commands that these things be examined or proven, or deemed worthy, what is the standard? Well, God's Word. Anything that the Christian participates in that is not deemed worthy of God's approval, is, well, "chasing after the wind", as is put in Ecclesiastes. Paul stated his life's goal in Philippians 3:10 and 14.
10 "That I may know him, and the power of his resurrection, and the fellowship of his sufferings, being made conformable unto his death;"
14 "I press toward the mark for the prize of the high calling of God in Christ Jesus."