yea black tees are offputting. Hard to wash, prefer white, it's a cooler colour. Black gets very hot. for me personally, would not wear black.
I like the verses you choose though.
Is the printing screen printed or is it embroidered or transfered? Sometimes those that are just stamped on run or fade and crack in the wash.
I have an idea. You know those letterman jackets universities have. well could sort of have that style lettering. Like the words 'Heaven' and 'school of the holy spirit', J for Jesus.
I liked it when Karen Carpenter had a t-shirt called 'lead sister'.
you could have 'brother' and 'sister' t shirts.
you could have stripy t shirts that say, by his stripes we are healed.
you could experiment with words 'agape' 'shalom' 'immanuel' 'talitha cumi' words that have deeper meaning you know only from reading the bible. People will ask the wearer what those words mean. Then maybe you could start a conversation.
(don't get it tattooed though. ugh. I am very against ppl who think it's godly to do that).
just some ideas. Good that you've got something already, can only get better!