“For all who have sinned without the Law will also perish without the Law, and all who have sinned under the Law will be judged by the Law; for it is not the hearers of the Law who are just before God, but the doers of the Law will be justified. For when Gentiles who do not have the Law do instinctively the things of the Law, these, not having the Law, are a law to themselves, in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or else defending them, on the day when, according to my gospel, God will judge the secrets of men through Christ Jesus.”
‭‭Romans‬ ‭2:12-16‬ ‭NASB‬‬

Being a Christian is not determined by whether you attend church, go to Sunday School, hold a position in the church, or even if you have a theological degree from a Christian institution. You can talk the lingo, share the rhetoric, go through the motions, and be a nice, moral person but that doesn't redeem you. You cannot simply identify yourself as Christian because you are a church going individual that carries a Bible, has a bumper sticker that says "honk if you love Jesus", have your name on the church membership roll, and have been raised in a Christian home. All of these things are great things but when it comes to the transformation of your sinful, wretched spirit there is only one cure - THE BLOOD OF JESUS!!! (See Ephesians 1:7; Colossians 2:14; I Peter 1:18-19 KJV).
I have said, in the pulpit at church, that there will be people in heaven that we thought were going to hell and there will be people in hell that we thought were going to heaven. Why? Because God, and God alone knows the true condition of someone's spirit. We see, and observe the outward person. God sees the spirit.
I can hear someone saying "I thought you had to live the Christian life to show that you are a follower of Jesus and to get to heaven!" Well, first of all, what is the Christian life? Is it doing what all of the other church people are doing or is it living like Christ? I submit to you that a true follower of Jesus will be a transformed person (see 2 Corinthians 5:17).  I also submit to you that a disciple of Jesus will desire to live like Jesus (see 1 John 2:6). However, we cannot say we are a follower of Jesus simply by going through the motions. We must have His Spirit (see Romans 8:9-11).
Whether we are Jew, Gentile, religious or not, we most certainly must be born again (see John 3:1-7). Correspondingly, it is important for a believer to be connected to a local church. Every baby needs a family and a home, every car needs a place to park, and every tree needs a place to be planted and grow. I believe that every believer needs a bible believing, preaching church to call home, and a place to belong and stay planted (see Hebrews 10:25).
Sitting on a pew doesn't make me a Christian any more than sitting at a gas station makes me a car. It is possible to be so religious that you are blinded by your own self righteousness. Do the right things, but be absolutely certain that Jesus has washed you in HIS BLOOD! Only then will you be acceptable to God!