God created the rainbow. The rainbow was a visual promise (covenant) to Noah of the Bible (and is to all flesh) that God will not flood the earth again. (see Genesis 9:14-17) The rainbow is beautiful because God created it that way.
I find it intriguing how we as human beings can fulfill Bible prophecy and God’s teachings without even knowing it. Look at Romans 8:7–“The mind that is set on the flesh is hostile to God, for it does not submit to God’s law; indeed, it cannot.” In other words, we naturally have a hatred directed at God. Enter the gay pride symbol: the rainbow. Human beings have taken something God intended beautiful and have trampled it underfoot by making it (the rainbow) a symbol for sinning against God. Therefore as the Bible already states, this is all done because it’s our nature to break God’s law (sin). Without being born again spiritually (to get a new heart from God) we will not be able to please Him nor will we have a Savior from the wrath to come.
“It is appointed for men to die once, but after this the judgment.” Hebrews 9:27
“He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him.” John 3:36
“God did not appoint us to wrath, but to obtain salvation through our Lord Jesus Christ” 1 Thessalonians 5:9
Lord is not slow to fulfill his promise as some count slowness, but is patient toward you, not wishing that any should perish, but that all should reach repentance. 2 Peter 3:9 ESV
Related interest: http://www.audacitymovie.com/