Lust, sexual desire or/and sexual fantasies aren't a sin, YHWH(The Father, and The Son, and The Holy Spirit) created it like food, false "atheistic" religions called YHWH's beauty a sin, I will prove it is not, do not let these religious secularist/"atheist"s fool you.
Matthew 5:27-28 in New International Version says, 27 “You have heard that it was said, ‘You shall not commit adultery.’[a] 28 But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.
Sorry but in Biblical study we use The Language in which YHWH gave us His Word, not faulty translations from man. this NIV translation is deceiving.
The Original Matthew 5:27-28 says in Koine Greek,
Matthew 5:27–28: Ἠκούσατε ὅτι ἐρρέθη· οὐ μοιχεύσεις. ἐγὼ δὲ λέγω ὑμῖν ὅτι πᾶς ὁ βλέπων γυναῖκα πρὸς τὸ ἐπιθυμῆσαι αὐτὴν ἤδη ἐμοίχευσεν αὐτὴν ἐν τῇ καρδίᾳ αὐτοῦ.
Key here is this part: πρὸς τὸ ἐπιθυμῆσαι
transliteration, pros to epithumesai
pros to comes BEFORE epithumesai
so now just like these verses, where it would be rendered IN ORDER TO,
“Beware of practicing your righteousness before men in order to be noticed by them.” (Matt 6:1)
Original Greek - Προσέχετε [a]δὲ τὴν δικαιοσύνην ὑμῶν μὴ ποιεῖν ἔμπροσθεν τῶν ἀνθρώπων πρὸς τὸ θεαθῆναι αὐτοῖς· εἰ δὲ μή γε, μισθὸν οὐκ ἔχετε παρὰ τῷ πατρὶ ὑμῶν τῷ ἐν τοῖς οὐρανοῖς.
“… First gather up the tares and bind them in bundles in order to burn them up ….” (Matt 13:30)
Original Greek, 30 ἄφετε συναυξάνεσθαι ἀμφότερα [a]μέχρι τοῦ θερισμοῦ· καὶ ἐν καιρῷ τοῦ θερισμοῦ ἐρῶ τοῖς θερισταῖς· Συλλέξατε πρῶτον τὰ ζιζάνια καὶ δήσατε αὐτὰ εἰς δέσμας πρὸς τὸ κατακαῦσαι αὐτά, τὸν δὲ σῖτον συναγάγετε εἰς τὴν ἀποθήκην μου.
“But they do all their deeds in order to be noticed by men; for they broaden their phylacteries and lengthen the tassels of their garments.” (Matt 23:5)
Original Greek - 5 πάντα δὲ τὰ ἔργα αὐτῶν ποιοῦσιν πρὸς τὸ θεαθῆναι τοῖς ἀνθρώποις· πλατύνουσι [a]γὰρ τὰ φυλακτήρια αὐτῶν καὶ μεγαλύνουσι τὰ κράσπεδα,
“For when she poured this perfume on my body, she did it in order to prepare me for burial.” (Matt 26:12)
Original Greek - 12 βαλοῦσα γὰρ αὕτη τὸ μύρον τοῦτο ἐπὶ τοῦ σώματός μου πρὸς τὸ ἐνταφιάσαι με ἐποίησεν.
All from Matthew.
So, Matthew 5:27-28 can be either of the following from the definition of epithumesai(which is verb), something you do, the one making no sense is void.
Here we go,
"You have heard that it was said, ‘Do not commit adultery.’ But I tell you that anyone who looks at a woman in order to lust after her has already committed adultery with her in his heart."
Lust is a desire, not an action even diliberate lust isn't doing something, an action is something you do, whoever looks at a woman in order to, means in order to do something, do what? lust is an emotion, a desire, etc, not an action, so this definition is null and void. if Jesus Christ meant lusting after a woman was a sin, then He would have said, whoever looks at a woman AND lust, etc, but He said whoever looks at a woman IN ORDER TO, so it's to do something, added with epithumesai is a verb, an action.
Since pros to makes this an action, whether you like it or not,
Now, the last definition would be Covet, lets see,
Matthew 5:27-28 - You have heard that it was said, ‘Do not commit adultery.’ But I tell you that anyone who looks at a woman in order to covet her has already committed adultery with her in his heart.
Added with the fact that the word for covet and woman/wife are the same in Exodus 20:17(Septuagint)
οὐκ ἐπιθυμήσεις τὴν γυναῖκα τοῦ πλησίον σου. οὐκ ἐπιθυμήσεις τὴν οἰκίαν τοῦ πλησίον σου οὔτε τὸν ἀγρὸν αὐτοῦ οὔτε τὸν παῖδα αὐτοῦ οὔτε τὴν παιδίσκην αὐτοῦ οὔτε τοῦ βοὸς αὐτοῦ οὔτε τοῦ ὑποζυγίου αὐτοῦ οὔτε παντὸς κτήνους αὐτοῦ οὔτε ὅσα τῷ πλησίον σού ἐστιν. (Ex 20:17 LXX)
Added with looks at a woman in order to.
The intent of the look for for a purpose, the purpose of what? in order to do what? and that in order to do is epithumesai(verb) her
So it should be rendered,
You have heard that it was said, ‘Do not commit adultery.’ But I tell you that anyone who looks at a married woman(as same word for woman/wife is used in Septuagint version of 10th Commandment) with the intention(due to looking at a woman in order to epithumesai(verb) her) of taking her(stealing her from the husband or cheating with her due to 10th Commandment) has already committed adultery(Sex between married person and someone outside of relationship, aka cheating) with her in his heart.
So Jesus Christ is just retelling the law(Thou Shall Not Commit Adultery and 10th Commandment), He never added to The Law, The Law He originally gave at The Exodus was Fine.
Now with this fact, that covet is an action and not a desire and as proven by http://Goddidntsaythat.com/2011/03/02/the-ten-commandments-dont-forbid-coveting/
Covet in The 10 Commandments means take.
why? read the link and the fact that The 8th Commandment "Thou Shall Not Steal" uses the word ganab which can mean Kidnap
God(The Father, The Son, and The Holy Spirit) gave commandments, prohibitions, on actions, which fits the entire context, desire is a natural thing that can BECOME sin, want proof?
James 1:15 - Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.
Natural Desire can cause sin but isn't sin, only an action or evil desires.
Therefore God(The Father, The Son, and The Holy Spirit) condemned slavery and sexually desiring a woman isn't a sin,
Proverbs 5:18-19 Let your fountain be blessed, and rejoice in the wife of your youth, a lovely deer, a graceful doe. Let her breasts fill you at all times with delight; be intoxicated always in her love
Song of Solomon 7:7-8
Your stature is like a palm tree, and your breasts are like its clusters. I say I will climb the palm tree and lay hold of its fruit. Oh may your breasts be like clusters of the vine, and the scent of your breath like apples,
Song of Solomon 8:10
I was a wall, and my breasts were like towers; then I was in his eyes as one who finds peace.
The True 10 Commandments are,
1, You shall have no other gods before Yahweh(The True God, The Trinity of The Father, and The Son, and The Holy Spirit)
2, You shall not make for yourself an image in the form of anything in heaven above or on the earth beneath or in the waters below.
3, Remember the Sabbath day by keeping it holy
4, You shall not misuse the name of the Lord your God, for the Lord will not hold anyone guiltless who misuses his name.
5, Honor your father and your mother, so that you may live long in the land the Lord your God is giving you.
6, You shall not murder.
7, You shall not commit adultery.
8, You shall not Kidnap
9, You shall not give false testimony against your neighbor.
10, “You shall not take(steal) your neighbor’s house. You shall not take(steal) your neighbor’s wife, or his male or female servant, his ox or donkey, or anything that belongs to your neighbor.”
and Matthew 5:27-28 is, "You have heard that it was said, ‘Do not commit adultery.’ But I tell you that anyone who looks at a married woman with the intention of taking her(stealing her from the husband or cheating with her) has already committed adultery with her in his heart."
Basically, Jesus Christ is saying, you know to not commit adultery, do not even plan or intend on taking(or cheating) with a woman, because it's as if you already did so.
Which fits well with The Rest of The Sermon of The Mount because remember,
Matthew 5:17 “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. 18 For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.
Jesus Christ never abolished or added any laws, The laws He gave at the exodus were fine.
For example on Oaths
Matthew 5:33 “Again, you have heard that it was said to the people long ago, ‘Do not break your oath, but fulfill to the Lord the vows you have made.’ 34 But I tell you, do not swear an oath at all: either by heaven, for it is God’s throne; 35 or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. 36 And do not swear by your head, for you cannot make even one hair white or black. 37 All you need to say is simply ‘Yes’ or ‘No’; anything beyond this comes from the evil one.[g]
Jesus Christ was just telling us how to accomplish the law, so for adultery(cheating, unfaithfulness, can only be committed by a married person and someone else(aka cheating) He said don't even plan to do it(like King David remember)
But lets use The Very Orthodox Books themselves(Early Church Fathers how the early Church in 2ND CENTURY had this verse to prove this,
"ἡ δὲ εὐαγγέλιος φωνὴ ἐπιτατικώτερον διδάσκει περὶ ἁγνείας λέγουσα· “Πᾶς ὁ ἰδὼν γυναῖκα ἀλλοτρίαν πρὸς τὸ ἐπιθυμῆσαι αὐτὴν ἤδη ἐμοίχευσεν αὐτὴν ἐν τῇ καρδίᾳ αὐτοῦ. καὶ ὁ γαμῶν”- Theophilus to Autolycus, B III, Ch 3
Key word? ἀλλοτρίαν which means, "belongeth to another"
Lust isn't a sin, Adultery is.
On other supposed verses on lust being sin,
I Peter 4:3
For the time past of our life may suffice us to have wrought the will of the Gentiles, when we walked in lasciviousness, lusts, excess of wine, revellings, banquetings, and abominable idolatries
On this verse, the word translated to lust in the Greek is again epithumeo; a longing (especially for what is forbidden), which fits well in the context, because Peter would have condemned a specific sexual behavior as well, he didn't even mention sexual sins, so this is about the crazy drugged up, drunken lifestyle that is condemned.
Even Peter 1 4:2 The Previous verse confirms this, http://interlinearbible.org/1_peter/4-2.htm as the same word is used,
"so as to live the rest of the time in the flesh no longer for the lusts of men, but for the will of God." Obviously sexual desire isn't being mentioned in that men but the desires of men, which is evil, and that we should no longer live for the lusts of men(sin and evil) but for The Will of God(YHWH: The Father, and The Son, and The Holy Spirit)
There ya go lust isn't a sin, even if you sexually desired a married woman it isn't a sin(only if you wanted to commit adultery is where you have sinned).
YHWH(The Father, and The Son, and The Holy Spirit) created sex, sexual desire, and physical beauty, so no it's not a sin to have good sexual fantasies, or to delight in a womans beauty, it's from YHWH.
What is sin would be harming or harmful fantasies , that has nothing to do with sex.
Proverbs 5:19 - A loving doe, a graceful deer-- may her breasts satisfy you always, may you ever be intoxicated with her love.
In Jesus Christ Name, God(YHWH: The Father and The Son(Jesus Christ) and The Holy Spirit) Bless.