If going to church does not make you a Christian, then not going to church does not make you not a Christian.
A saved Christian believer is one who believes in Jesus as his or her Savior from sin, eternal death, and Hell.
There are all kinds of churches today that are wrongly and unbiblically adding to God’s simple biblical command to believe in Jesus for salvation (a reference to this command, and Jesus’ personal guarantee of salvation, is found in my favorite Bible verse, John 6:47).
Every person who has, in a moment of time, simply believed in the perfect, holy, and sinless man, Christ Jesus, crucified on the cross, dead, and risen again to life, as their divine Savior, is already forgiven of all their sins (past, present and future), they are already permanently declared “not guilty” of sin by God (justification), they are already members of Jesus’ church, they are already the sons and daughters of God, they are already permanently indwelled by the Holy Spirit, they are already spiritually baptized into Christ’s death and resurrection, and they are already irrevocably guaranteed to go to Heaven and to live with God in joy and bliss eternally.
No church membership, slavery to a church council, regular church attendance, or baptism into ~water~ is going to make their salvation any more secure than God has already made it.
Of course, it is God’s will that believers in Jesus follow the Spirit, assemble with other believers, worship Him as a body of believers, do good works, and grow in His grace, fellowship, sanctification, and love–but these things are not requirements for salvation.