The Roman Catholic Church had a strong policy of changing or destroying pagan names or other references from several things. Why they didn't rename the classical planets (Mercury, Venus, Mars, Jupiter and Saturn)? They are essentially named after Roman mythological gods (that makes them pagan connotations).
Isidore of Seville is a well-known writer of the 7th century, whose encyclopedical works were widely read in the early middle ages.
His main work, the Etymologiae tries to collect the essence of knowledge of Antiquity. It also contains a chapter about astronomy. Concerning the names of the planets, he condems their naming after false gods:
(English translation Stephen A. Barney et al., Cambridge University Press 2006)
Planets are stars that are not fixed in the sky as the rest are...Their Greek names are Phaeton, Phaenon, Pyrion, Hesperus, and Stilbon. The Romans have consecrated them with the names of their gods, that is, Jupiter, Saturn, Mars, Venus, and Mercury. Themselves deceived, and wishing to deceive others into the worship of those who had granted them something in accordance with their desires, they would point out stars in the sky, and say that this on was Jupiter's and that one was Mercury's, and this vain belief was born. The devil strengthened this errroneous belief, and Christ overturned it.
But no "Christian" names are then given.
Another work, De natura rerum, On the nature of things, is a complilation of christian thoughts about natural history, giving a lot of weight to the scriptures and the writings of the Church Fathers.
Chapter 26: De nominibus atstrorum, The names of the stars has some general thoughts about the naming of stars (Chapter 13 handles the planets, but just uses their names as a given):
Legitur in Iob dicente domino: 'Numquid coniungere vales micantes stellas Pliades et gyrum arcturi poteris dissipare? Numquid producis Luciferum in tempore suo et vesperum super filios terrae consurgere facis?' Et iterum alibi: 'Qui facit arcturum et Orionem et Hyadas.' Haec nomina stellarum dum in scripturis sacris legimus vanis deliramentis poetarum adsensum non praebeamus, qui falsis opinionibus ista in astris ex hominum nominibus vel aliarum creaturam vocabulis inposerunt. Ita enim stellarum quarundam gentilium sapientes nomina sicut et dierum indiderunt.
Quod vero isdem nominibus sacra utitur scriptura, non eorum idcirco vanas adprobat fabulas, sed faciens ex rebus visibilibus invisibilium rerum figuras ea nomina pro cognitione hominum ponit, quae late sunt cognita, ut quidquid incocgnitum significat, facilus per id quod est cognitum humanis sensibus innotescat.
(Translation by Google translator.)
It is read in Job saying to the Lord: 'Are you able to unite the twinkling stars of the Pleiades and to dispel the whirlwind of Arcturus? Dost thou bring forth Lucifer¹ in its season, and make the evening rise upon the children of the earth?' [Job 38:31-32] And again in another place: 'Who makes Arcturus and Orion and the Hyades.' [Job 9:9] While we read these names of the stars in the sacred writings, let us not give assent to the vain delirium of the poets, who, by false beliefs, have imposed these names on the stars from the names of men or the terms of other creatures. For thus the wise men of certain Gentiles gave names to the stars, just as they did to the days.
But the fact that the sacred scriptures use the same names does not therefore approve of their vain fables, but, making figures of invisible things out of visible things, sets forth those names for the knowledge of men, which are widely known, so that whatever signifies the unknown, may easily be known to the human senses by that which is known.
In short: the names of the stars are made-up by men anyway, let's leave them alone so that everyone knows what we are talking about.
¹ Lucifer here refers to the name of the Morning Star. Venus in Antiquity was considered to be two different stars, the Evening Star Hesperos/Venus, and the Morning Star Phosphoros/Lucifer.