But - . -- The Greek word translated as "but" means "but," "however," and "on the other hand." It joins phrases in an adversarial way.

if -- The "if" here expresses a condition but it means nothing regarding whether that condition is met or not. It also means "if ever" and "whenever."

it is -- (IW) There is nothing that can be translated as "it is" in the Greek source.

by   - The word translated as "by" primarily means "in," "with," and "into." It means "by" in the sense of "near." It means "in" in the sense of "in the name of" or "by the power of." 

the -- (IW) There is nothing that can be translated as "the" in the Greek source.

Spirit  - The Greek word for "spirit" also means "breath" or "wind." Christ uses it to describe the invisible force that animates living creatures. God is the primary, invisible animating force. However, this is not "the Spirit." The Greek article ("the") is not used. The sense is "a spirit." 

of -- This word "of"  comes from the genitive case of the following word that requires the addition of a preposition in English.  The most common is the "of" of possession.

missing "the"  -- (MW) The untranslated word is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those"). See this article for more. 

God,  - The word translated as "God' means "God" and "deity."  Christ usually uses this word with an article "the God" to refer to the Father, but here he doesn't use the article so "a god" or "a deity." 

that -- (IW) There is nothing that can be translated as "that" in the Greek source.

I  - (MW) The pronoun "I" is used here. Since, as the subject of the sentence, it is part of the verb, its explicit use accentuates who is speaking "I." In English, we do something similar saying "I myself." 

drive - "Drive " is a Greek verb that means "throw out." Depending on the context, it can mean "toss out," "turn out," or "take out." It is usually translated as "cast out" in the NT.

out  -- This is from the prefix that means "out of" or "from"of the previous verb.

missing "the"  -- (MW) The untranslated word is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those"). See this article for more. 

demons,  - "Demons" is a Greek word that means "divinity," "divine power," "a lower divine being," and "evil spirit. "Evil spirit" is a New Testament usage or interpretation. More about Biblical use in this article.) Today, we would use a psychological term for these disorders, like "delusions," or, "personal demons."

then --  (CW) The word translated as "then" is a particle marking a sudden change or explaining or drawing attention to a consequence of an action. It is used in questions that expect a negative answer. With the objective negative, it expects a positive answer. It is not one of the words commonly translated as "then" or "therefore."

the .  -- The word translated as "the" is the Greek definite article. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

kingdom  - "Kingdom" is a Greek word that means "kingdom," "dominion," "royal power," and "reign." It is the same word used in the phrase "kingdom of heaven." It means that which is ruled by a specific person. It is not a synonym for a state, a country, or any social group of people. It is defined by its control or ownership by a master and refers both to people, organizations, and property under that control (see this article on the use of the "kingdom of heaven").

of -- This word "of"  comes from the genitive case of the following word that requires the addition of a preposition in English.  The most common is the "of" of possession.

missing "the"  -- (MW) The untranslated word is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those"). See this article for more. 

God - - The word translated as "God' means "God" and "deity."  Christ usually uses this word with an article "the God" to refer to the Father, but here he doesn't use the article so "a god" or "a deity." The phrase, "the kingdom of God" appears at the very end of the verse, not in the middle. It is the punch-line. 

has .-  This helping verb indicates the present tense of the verb, but the sense means "at a point in time" either in the past, present, or future.

come " - (CW) ""Come" is a Greek verb that actually means "to come or do first." It has the sense of overtaking someone or beating them in a race. This and a similar verse in Luke are the only times Jesus uses this word. This is not the common Greek word translated as "come" in the NT. A normal Greek translation would be "overtook you" or, since a preposition is used, "caught up to you." However, from the OT verse quoted, the sense seems ot be more "reach" or "attain"

unto  - -- The word translated as "unto" means "on," "over," "upon," "against," "before," "after," "during," "by" or "on." With the accusative object, as we see here, it means of place: "upon or on to a height," "up to," "as far as," "a little way," "a little," "towards," "to," in hostile sense: "against," of extension: "over," "over (a space)," of time: "for," "during," "up to" or "till," in a causal sense: "of (the object)," for (this purpose)," "as regards," "according to," and "by (this cause)."

you. - -- The "you" here is the second-person, plural pronoun in the form of an object.