Because of the depravity or spiritual death of man !
Even though false religion refuses to bow down to divine revelation that man in the flesh cannot come / believe on Christ, yet its true anyway, and that's why God's Elect must be drawn to Christ by the Father, which drawing is by the Spirit of God !
John 6:44
44 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.
Folks, this statement " no man can come to me " MEANS Believe on Him, come to Him in Faith ! No man can do that, that demolishes the false teaching of freewill right there !
Now the word draw here is a strong word, because it denotes God's Power, the Power of the Holy Spirit, its the greek word helkō and means:
I.
to draw, drag off
II.
metaph., to draw by inward power, lead, impel
Jesus means this metaph use, to draw by inward power or lead or impel. Remember Jesus said of His Sheep that He leads them out Jn 10:1-4
Verily, verily, I say unto you, He that entereth not by the door into the sheepfold, but climbeth up some other way, the same is a thief and a robber.
2 But he that entereth in by the door is the shepherd of the sheep.
3 To him the porter openeth; and the sheep hear his voice: and he calleth his own sheep by name, and leadeth them out.
4 And when he putteth forth his own sheep, he goeth before them, and the sheep follow him: for they know his voice.
It can be said " He fetches them out " or that He brings them out, the point being, its done by Him, His Power ! This is the ideal of Jn 6:44 that they are drawn, and its the Power of the Spirit to be exact.
God's Spirit and His Work is related to Power for instance here Zech 4:6
6 Then he answered and spake unto me, saying, This is the word of the Lord unto Zerubbabel, saying, Not by might, nor by power, but by my spirit, saith the Lord of hosts.
Now the context of this verse is about the building of the Temple of God, and that it was going to be accomplished by God's Spirit ! And so it is with the Spiritual Temple of God, the Church 1 Cor 3:16
16 Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you?
Paul is speaking of the Body of Christ here See 1 Cor 12 !
Also Eph 2:21-22
21 In whom all the building fitly framed together groweth unto an holy temple in the Lord:
22 In whom ye also are builded together for an habitation of God through the Spirit.
2 Cor 6:16
16 And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.
This Temple comprised of Believers was made by the Power and Might of the Spirit, by His Making them Alive by Regeneration, Spiritual quickening, making dead stones into Living Stones 1 Pet 2:5
5 Ye also, as lively stones, are built up a spiritual house [Temple], an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.
And so hecnce the drawing is by the Power and Might of the Spirit 1 Thess 1:5
5 For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
And so it becomes an inward compelling or impelling by the Spirit ! 5