What is the function of Trinity Sunday? Readings just don’t explain it! Why is it important that we speak correctly about The Father, The Son and The Holy Spirit?

Matthew 28:16-20 Now the eleven disciples went to Galilee, to the mountain to which Jesus had directed them. And when they saw him they worshiped him, but some doubted. And Jesus came and said to them, “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.”