"Folly is joy to him who is destitute of discernment, but a man of understanding walks uprightly" (Proverbs 15:21).
Mario was a faithful follower of God. But one day he found himself alienated from God after walking through open doors of opportunity. He went overseas to work with a large salary and travel perks, leaving behind a family who loves him. He allowed himself to believe that God was blessing him and his family because He had opened all doors. He had an affair and lost his family along the way. Most importantly, although he got what he wanted, he lost what he needed the most -- a close, saving relationship with God.
We all need true discernment to determine which opportunities are from God. It is because evil often wears a mask. When a door of opportunity opens, we should not automatically assume that it's God's will for us to go through it. Just because He doesn't stop us doesn't mean He wants us to pursue it.
To discern which "open doors" are from the Lord, we have to seek to "approve the things that are excellent" and "to be filled with the fruits of righteousness ... to the glory and praise of God" (Scripture: Philippians 1: 10, 11).