req.isAuthenticated() always returns false - node.js

Question

I am new to the Passport.js. Whenever I login or register through the routes, req.isAuthenticated() always returns false and the secrets view is never rendered. Here is my app.js:
`
require("dotenv").config();
const express = require("express");
const bodyParser = require("body-parser");
const session = require("express-session");
const passport = require("passport");
const LocalStrategy = require("passport-local")
const passportLocalMongoose = require("passport-local-mongoose");
const mongoose = require("mongoose");
mongoose.set("strictQuery", true);
uri = "mongodb://localhost:27017/usersDB";
const userSchema = new mongoose.Schema({
username: String,
password: String
});
userSchema.plugin(passportLocalMongoose);
const User = new mongoose.model("User", userSchema);
passport.use(new LocalStrategy(User.authenticate()));
passport.serializeUser(User.serializeUser());
passport.deserializeUser(User.deserializeUser());
const app = express();
app.use(bodyParser.urlencoded({extended: true}));
app.use(express.static("public"));
app.set("view engine", "ejs");
app.use(session({
secret: "MyLittleSecret",
resave: false,
saveUninitialized: false
}));
app.use(passport.initialize());
app.use(passport.session());
app.get("/", function(req, res) {
res.render("home");
});
app.get("/secrets", function(req, res) {
if(req.isAuthenticated) {
res.render("secrets");
} else {
res.redirect("/login");
}
});
app.route("/register")
.get(function(req, res) {
res.render("register");
})
.post(async function(req, res) {
await User.register({username: req.body.username}, req.body.password, function(err, user) {
console.log("In the User.register callback function");
if(err) {
console.log(err);
res.redirect("/register");
} else {
passport.authenticate("local")(req, res, function() {
res.redirect("/secrets");
});
}
});
});
app.route("/login")
.get(function(req, res) {
res.render("login",{
errorMessage: ""
});
})
.post(async function(req, res) {
const userInstance = new User({
username: req.body.username,
password: req.body.password
});
req.login(userInstance, function(err) {
if(err) {
console.log(err);
} else {
passport.authenticate("local")(req,res,function() {
res.redirect("/secrets");
});
}
});
});
app.listen(3000, function() {
console.log("Server started listening to port 3000");
});
I searched on the web and tried the various orders of middleware. I could not solve the problem.