I've seen this portion of Scripture interpreted many different ways. The one that makes the most sense to me is:
The Wide Gate - the external - the things of men - the shows of men - Pharisees being an example.
The Narrow Gate - the internal - the things of God - the heart - Jesus Christ being the only way.
Many people do warm church pews and have an outward show that means nothing to God. God looks at the heart. The Holy Spirit of God is living in the heart of a real Christian.
The wide gate might be people trying to be good - thinking that they can work their way or earn their way to heaven. They can't - not a single person has ever been saved by works, obeying the law, or establishing their own righteousness.
It all boils down to only one way:
John 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
Romans 10:8-10 But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach; 9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. 10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
Love In Christ,