This passage is described as the exit from the Sermon on the Mount. Notice how Jesus starts with the 2nd person imperatives (do this in verse 12, Enter in 13, Beware in 15) and moves to the third person (Not everyone in verse 21). The imperatives are for his disciples (including us) and warn us that our faith walk will not always be the easy path to take and there are many who would try to pull us away from Christ.
It’s not easy to enter by the narrow gate, especially when we see people who seem to be rewarded for blatantly living opposed to Christ’s will and commands. It’s hard to stay on that narrow path when we hear false prophets telling us the so-called prosperity gospel of “you can have your best life now” as the central message of the Bible. It’s much easier to walk the wide path and listen to those who tell us that in order to be a better Christian we need to do this or that.
The gate is narrow because it there is only one way to enter it – not by wealth or actions or words, but simply by faith in Jesus. No things to be done, hoops to jump through or even a prayer to pray, but simply by trusting in the one who paid the price for us!