Is art made by a Christian artist but that does not show a "religious" picture or mention "religious" words, still Christian art?

First consider this: Jesus’s parables were stories that did not always mention God. Does this make them non-Christian stories?

Second consider this: Trees are a creation not unlike a piece of artwork. They do not have any religious connection that is obvious to the observer. Does that make them secular art?

Conclusion: Art done by a Christian is Christian art (see the exclusion below).

Lesson: First impressions are important. The first verse in the Bible is "In the beginning, God created…" God showed immense (to our minds) variety when he created the universe. He obviously likes variety and likes to create. Most things he created are pleasing to most eyes. If they are not "pleasing" they are at least creative.

Look at a peacock. Look at a fangtooth fish. God did not make everything gold.

He created us in His image, allowing us intellectual creativity, unlike any other living thing. I hardly think he expected us all to limit our creativity by requiring we picture his name and symbols on everything we do. (Duty reduces the dance to a drill- John Eldredge)(1 Cor 12:27-29) If we truly love Him and desire to serve Him, then the gifts that he gave us will come through in our hands, voices, minds, philosophies, etc. I am sure some are called to do "religious art" but I am just as certain that others are not. (For it is God who works in you to will and to act according to his good purpose. Phil 2:13) Giving glory to God in our art means developing the gift He gave us to the fullest.

The exception to "art done by Christian being Christian art": Not everything we do is acceptable to God. If art is done with a sinful attitude, it is surely done wrong. This would include art that causes someone to sin.