OK, a lot of directions that can be gone on a Sunday like this artwise…talking specifically about the Trinity there are images like:
Icon of the Council of Nicea
Since the Council of Nicea is where the language of God as Trinity became the official doctrine of the church in 325
Rublev’s Icon of the Holy Trinity
Trinity with Christ Crucified, Austrian about 1410
For the first reading about the creation there are also a plethora of images, here are some varied images I like:
Lukas Cranach, Day 7 Shabbat, The Rest of God and Man, from the Lutherbibel (1534)
William Blake, The Ancient of Days: The Division of Light and Darkness (1794)
I like this particular nebula because it is where the formation the Pillars of Creation is
Origins of Creation by nisht@deviantart.com
Creation by OneLifeOneArt@deviantart.com
And for the Great Commission in Matthew’s Gospel:
Christoph Wiegel, The Great Commission
Stained glass window by David J. Hetland
Sign of the Rose 