There is so much strong liturgical material to play with in these readings that it’s quite a challenge to narrow down options – Creation, the Great Commission and the Grace! And that’s before you even look at picking up the theme of the Trinity.
It feels like there are two possible options for your gathering time, either songs which set out the Trinitarian theme from the beginning, or songs which root your worship in praise for God the maker of all things.
The classic Trinitarian opener would be Holy, holy, holy, Lord God almighty (CH 111 / MP 237) which can be accompanied in a whole range of styles and instrumentation. Today I awake (CH 211) has a similar structure and some wonderful imagery with a tune that is well worth learning. Source and Sovereign, Rock and Cloud (CH 133) does the incredible task of giving twelve names for each member of the Trinity set to the majestic tune Aberystwyth. Our God saves (CCLI / MP 1192) is explicitly Trinitarian in the way few songs of its style are while Jesus lead us to the Father (Resound) is fast becoming a modern classic. It can simply be sung in unison but when used as a round it can really build a wonderful time of praise.
Picking up the Creation theme could give a really energetic opening. Uyai mose / Come all you people (CH 757 / Wild Goose) from Zimbabwe can be sung a capella or unaccompanied (you could also make it Trinitarian by changing “Maker” to “Saviour” and “Spirit”). Sing for God’s glory (CH 172) has great words and also an arrangement that helps get a decent speed for a tune which can sometimes be a bit of a dirge (make sure to sing it in one in a bar). From life’s beginning / Let praise resound (Resound) is a really uplifting call to worship that is tightly themed around Creation in a way few songs of its style have done. There are quite a few songs called Let there be light (CCLI / YouTube) but I really like this version by Canadian band The City Harmonic.
An interesting choice to set the tone for the reading of scripture could be She sits like a bird / Enemy of Apathy (CH 593 / Wild Goose). It starts with imagery from Genesis 1:2 of the place of the Spirit in Creation and moves by the final verse to her being the key to opening the scriptures. By Faith (Getty / MP 1262) also takes Creation as its starting point and then moves us to the promise found in scripture.
There are two good options in CH4 for singing the psalm, although I would probably choose a different tune for How excellent in all the earth (CH 4) unless you want people to be put straight back into a Christmas mood. Stroudwater or Irish would suit the text well. O Lord, our Lord, throughout the earth (CH 5 / Wild Goose) is quite a lengthy tune but adds a suitably robust energy to the text. If it’s not well known to your congregation then the Coda (essentially the first two lines) would work well as a responsorial psalm.
With the length of the Genesis text you might also consider splitting it up with a sung response after each day. The same small part of the psalm mentioned above could work, or else a more general option might be an Alleluia. There are lots of great options for this and it could be an opportunity to sing in simple parts (CH341, CH751, CH 752).
Choices here very much depend on the themes being preached on but there are some good general Trinitarian songs which might be useful such as O threefold God of tender unity (CH 114), Loving Creator (CH 116) and Mothering God, you gave me birth (CH 117 / Wild Goose), the latter based on a text by Julian of Norwich, something worth remembering when people say feminine imagery for God is a modern invention.
If you are exploring the Gospel text then there are some short chants on themes of peace and reconciliation which could fit well. Ososo / Come now, O Prince of peace (CH 275 / Wild Goose) is one of a number of Korean songs on these themes, perhaps not surprising in a divided country. Confitemini Domino / Come and fill our hearts (Taizé) is a simple chant that is coloured beautifully by the unexpected harmony on the second Domino.
There are three strong themes you might use in the end the service – either tying up the Trinitarian theme, using the Gospel text of the Great Commission as a call to mission, or focusing on the Epistle. It could be possible to use more than one liturgically but more tricky musically as they have such different energies, so having a strong idea of what the purpose of this part of the service is will be key to your choices.
There are some wonderful Trinitarian hymns set to older tunes which can provide a suitably heightened conclusion such as I bind unto myself today (CH 639) or God, whose almighty word (CH 112). This is a more challenging theme to find in well-known contemporary songs but is picked up in How great is our God (CCLI / MP 1227) which is often followed with a chorus of How great thou art (CH 154 / MP 506)
The action of sending out in mission is explicitly picked up in Go in grace and make disciples (CH 682) and Mission’s Flame (CCLI). Given the call is to “make disciples of all nations” it could be good to use a song from another country and one of my favourite songs I’ve learned in recent years is Murassalat (H 82 / YouTube). This is a wonderful song from South Sudan which calls on us all to be ambassadors of Jesus and works just as well with a band as it does a cappella (watch out for it on a new Wild Goose album later this year).
Finishing with a sung blessing picking up on the themes from 2 Corinthians would be a quieter ending but not necessarily any less uplifting, especially if repeated a few times. May the God of peace go with us (CH 786) will be a well known tune to many in Scotland. May the Lord mighty God (CH 787 / Wild Goose) is a beautiful song from China, especially if you have some people who can sing the second part. May the Grace (Resound) is one of the few songs which sets these verses explicitly, also adding the Aaronic Blessing.